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Gartner Inc – ‘10-K’ for 12/31/16 – ‘EX-101.LAB’

On:  Wednesday, 2/22/17, at 4:10pm ET   ·   For:  12/31/16   ·   Accession #:  749251-17-5   ·   File #:  1-14443

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  As Of               Filer                 Filing    For·On·As Docs:Size

 2/22/17  Gartner Inc                       10-K       12/31/16  100:11M

Annual Report   —   Form 10-K   —   Sect. 13 / 15(d) – SEA’34
Filing Table of Contents

Document/Exhibit                   Description                      Pages   Size 

 1: 10-K        Annual Report                                       HTML   1.02M 
 2: EX-21.1     Subsidiaries List                                   HTML     46K 
 3: EX-23.1     Consent of Experts or Counsel                       HTML     29K 
 4: EX-31.1     Certification -- §302 - SOA'02                      HTML     35K 
 5: EX-31.2     Certification -- §302 - SOA'02                      HTML     36K 
 6: EX-32       Certification -- §906 - SOA'02                      HTML     31K 
13: R1          Document And Entity Information                     HTML     56K 
14: R2          Consolidated Balance Sheets                         HTML    104K 
15: R3          Consolidated Balance Sheets (Parentheticals)        HTML     49K 
16: R4          Consolidated Statements of Operations               HTML     89K 
17: R5          Consolidated Statements of Comprehensive Income     HTML     51K 
18: R6          Consolidated Statements of Stockholders' Equity     HTML     68K 
                (Deficit)                                                        
19: R7          Consolidated Statements of Cash Flows               HTML    115K 
20: R8          Business and Significant Accounting Policies        HTML    230K 
21: R9          Acquisitions                                        HTML     51K 
22: R10         Other Assets                                        HTML     38K 
23: R11         Accounts Payable, Accrued, and Other Liabilities    HTML     54K 
24: R12         Debt                                                HTML     62K 
25: R13         Commitments and Contingencies                       HTML     41K 
26: R14         Stockholders' Equity (Deficit)                      HTML    101K 
27: R15         Stock-Based Compensation                            HTML    136K 
28: R16         Computation of Earnings Per Share                   HTML     62K 
29: R17         Income Taxes                                        HTML    145K 
30: R18         Derivatives and Hedging                             HTML     89K 
31: R19         Fair Value Disclosures                              HTML     75K 
32: R20         Employee Benefits                                   HTML    107K 
33: R21         Segment Information                                 HTML    142K 
34: R22         Valuation and Qualifying Accounts                   HTML     58K 
35: R23         Subsequent Events                                   HTML     35K 
36: R24         Business and Significant Accounting Policies        HTML    181K 
                (Policies)                                                       
37: R25         Business and Significant Accounting Policies        HTML    166K 
                (Tables)                                                         
38: R26         Other Assets (Tables)                               HTML     38K 
39: R27         Accounts Payable, Accrued, and Other Liabilities    HTML     56K 
                (Tables)                                                         
40: R28         Debt (Tables)                                       HTML     49K 
41: R29         Commitments and Contingencies (Tables)              HTML     37K 
42: R30         Stockholders' Equity (Deficit) (Tables)             HTML     99K 
43: R31         Stock-Based Compensation (Tables)                   HTML    130K 
44: R32         Computation of Earnings Per Share (Tables)          HTML     63K 
45: R33         Income Taxes (Tables)                               HTML    138K 
46: R34         Derivatives and Hedging (Tables)                    HTML     84K 
47: R35         Fair Value Disclosures (Tables)                     HTML     67K 
48: R36         Employee Benefits (Tables)                          HTML    107K 
49: R37         Segment Information (Tables)                        HTML    140K 
50: R38         Valuation and Qualifying Accounts (Tables)          HTML     57K 
51: R39         Business and Significant Accounting Policies        HTML     98K 
                (Detail)                                                         
52: R40         Business and Significant Accounting Policies        HTML     58K 
                (Detail) - Property, Equipment and Leasehold                     
                Improvements, Less Accumulated Depreciation and                  
                Amortization                                                     
53: R41         Business and Significant Accounting Policies        HTML     63K 
                (Detail) - Intangible Assets Subject to                          
                Amortization                                                     
54: R42         Business and Significant Accounting Policies        HTML     42K 
                (Detail) - Estimated Future Amortization Expense                 
                by Year from Purchased Intangibles                               
55: R43         Business and Significant Accounting Policies        HTML     52K 
                (Detail) - Changes to the Carrying Amount of                     
                Goodwill by Reporting Unit                                       
56: R44         Business and Significant Accounting Policies        HTML     68K 
                Business and Significant Accounting Policies                     
                (Detail) - New Accounting Pronouncements                         
57: R45         Acquisitions - (Details)                            HTML    107K 
58: R46         Other Assets (Detail) - Composition of Other        HTML     38K 
                Assets                                                           
59: R47         Accounts Payable, Accrued, and Other Liabilities    HTML     50K 
                (Detail) - Accounts Payable and Accrued                          
                Liabilities                                                      
60: R48         Accounts Payable, Accrued, and Other Liabilities    HTML     45K 
                (Detail) - Other Liabilities                                     
61: R49         Debt (Detail)                                       HTML    117K 
62: R50         Debt (Detail) - Borrowings                          HTML     43K 
63: R51         Commitments and Contingencies (Detail) - Future     HTML     47K 
                Minimum Annual Cash Payments Under Non-Cancelable                
                Operating Lease Agreements                                       
64: R52         Stockholders' Equity (Deficit) (Detail)             HTML     49K 
65: R53         Stockholders' Equity (Deficit) (Detail) - Summary   HTML     42K 
                of Transactions Relating to Common Stock                         
66: R54         Stockholders' Equity (Deficit) (Details) - Changes  HTML     60K 
                in AOCL/I by Component                                           
67: R55         Stock-Based Compensation (Detail)                   HTML    114K 
68: R56         Stock-Based Compensation (Detail) - Stock-Based     HTML     39K 
                Compensation Expense By Award Type                               
69: R57         Stock-Based Compensation (Detail) - Stock-Based     HTML     37K 
                Compensation Expense Recognized In Consolidated                  
                Statements Of Operations                                         
70: R58         Stock-Based Compensation (Detail) -                 HTML     41K 
                Weighted-Average Assumptions Used To Determine                   
                Fair Value Of SARs Grants On Date Of Grant Using                 
                Black-Scholes-Merton Valuation Model                             
71: R59         Stock-Based Compensation (Detail) - Summary Of      HTML     80K 
                Changes In SARs Outstanding                                      
72: R60         Stock-Based Compensation (Detail) - Summary Of      HTML     52K 
                Changes In RSUs Outstanding                                      
73: R61         Stock-Based Compensation (Detail) - Summary Of      HTML     47K 
                Changes In CSEs Outstanding                                      
74: R62         Computation of Earnings Per Share (Detail)          HTML     33K 
75: R63         Computation of Earnings Per Share (Detail) -        HTML     53K 
                Calculations Of Basic And Diluted Earnings Per                   
                Share                                                            
76: R64         Computation of Earnings Per Share (Detail) -        HTML     34K 
                Common Share Equivalents Not Included in the                     
                Computation of Diluted EPS                                       
77: R65         Income Taxes (Detail)                               HTML    100K 
78: R66         Income Taxes (Detail) - Summary of Components of    HTML     36K 
                Income Before Income Taxes                                       
79: R67         Income Taxes (Detail) - Components of Income Tax    HTML     71K 
                Expenses                                                         
80: R68         Income Taxes (Detail) - Current and Long-Term       HTML     58K 
                Deferred Tax Assets and Liabilities                              
81: R69         Income Taxes (Detail) - Differences Between U.S.    HTML     56K 
                Federal Statutory Income Tax Rate and Effective                  
                Tax Rate on Income Before Income Taxes                           
82: R70         Income Taxes (Detail) - Reconciliation of           HTML     45K 
                Beginning and Ending Amount of Unrecognized Tax                  
                Benefits, Excluding Interest and Penalties                       
83: R71         Derivatives and Hedging (Detail) - Outstanding      HTML     49K 
                Derivatives Contracts                                            
84: R72         Derivatives and Hedging (Detail) - Derivative       HTML     36K 
                Gains And Losses That Have Been Recognized In                    
                Condensed Consolidated Statements Of Operations                  
85: R73         Fair Value Disclosures (Detail)                     HTML     35K 
86: R74         Fair Value Disclosures (Detail) - Assets And        HTML     57K 
                Liabilities Measured At Fair Value On Recurring                  
                Basis                                                            
87: R75         Employee Benefits (Detail)                          HTML     80K 
88: R76         Employee Benefits (Detail) - Components of Net      HTML     45K 
                Periodic Pension Expense                                         
89: R77         Employee Benefits (Detail) - Assumptions Used in    HTML     33K 
                Computation of Net Periodic Pension Expense                      
90: R78         Employee Benefits (Detail) - Information Related    HTML     49K 
                to Changes in Projected Benefit Obligation                       
91: R79         Employee Benefits (Detail) - Benefit Plans and      HTML     47K 
                Related Amounts Recorded in Consolidated Balance                 
                Sheets                                                           
92: R80         Segment Information (Detail)                        HTML     33K 
93: R81         Segment Information (Detail) - Information About    HTML     48K 
                Reportable Segments                                              
94: R82         Segment Information (Detail) - Reconciliation of    HTML     57K 
                Segment Gross Contribution to Net Income                         
95: R83         Segment Information (Detail) - Summarized           HTML     46K 
                Information by Geographic Location                               
96: R84         Valuation and Qualifying Accounts (Detail) -        HTML     39K 
                Summarized Activity in Allowances                                
97: R85         Subsequent Events - (Details)                       HTML     45K 
99: XML         IDEA XML File -- Filing Summary                      XML    192K 
98: EXCEL       IDEA Workbook of Financial Reports                  XLSX    125K 
 7: EX-101.INS  XBRL Instance -- it-20161231                         XML   3.32M 
 9: EX-101.CAL  XBRL Calculations -- it-20161231_cal                 XML    295K 
10: EX-101.DEF  XBRL Definitions -- it-20161231_def                  XML    892K 
11: EX-101.LAB  XBRL Labels -- it-20161231_lab                       XML   2.16M 
12: EX-101.PRE  XBRL Presentations -- it-20161231_pre                XML   1.35M 
 8: EX-101.SCH  XBRL Schema -- it-20161231                           XSD    224K 
100: ZIP         XBRL Zipped Folder -- 0000749251-17-000005-xbrl      Zip    331K

‘EX-101.LAB’   —   XBRL Labels — it-20161231_lab

This Exhibit is an XBRL XML File.

                                                                                                                                                                                
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<link:label id="lab_us-gaap_CostOfSalesMember_E204FD7D04418C13334CE53BFB414958_terseLabel_en-US" xlink:label="lab_us-gaap_CostOfSalesMember_E204FD7D04418C13334CE53BFB414958" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Costs of services and product development </link:label>
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<link:label id="lab_us-gaap_NetIncomeLoss_BE5BCAD2F8ADCC5A4738CD057C0E7C95_label_en-US" xlink:label="lab_us-gaap_NetIncomeLoss_BE5BCAD2F8ADCC5A4738CD057C0E7C95" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Net Income (Loss) Attributable to Parent </link:label>
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<link:label id="lab_us-gaap_OtherComprehensiveIncomeLossForeignCurrencyTransactionAndTranslationAdjustmentNetOfTax_ADE5043225210B3EE743CD2C416F95DF_label_en-US" xlink:label="lab_us-gaap_OtherComprehensiveIncomeLossForeignCurrencyTransactionAndTranslationAdjustmentNetOfTax_ADE5043225210B3EE743CD2C416F95DF" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_OtherComprehensiveIncomeLossForeignCurrencyTransactionAndTranslationAdjustmentNetOfTax" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossForeignCurrencyTransactionAndTranslationAdjustmentNetOfTax_ADE5043225210B3EE743CD2C416F95DF" xlink:type="locator"/>
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<link:label id="lab_us-gaap_OtherComprehensiveIncomeUnrealizedGainLossOnDerivativesArisingDuringPeriodNetOfTax_63FB1A417172E823C129CD2C9681A682_terseLabel_en-US" xlink:label="lab_us-gaap_OtherComprehensiveIncomeUnrealizedGainLossOnDerivativesArisingDuringPeriodNetOfTax_63FB1A417172E823C129CD2C9681A682" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Interest rate hedges - net change in deferred loss </link:label>
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<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_OtherComprehensiveIncomeUnrealizedGainLossOnDerivativesArisingDuringPeriodNetOfTax" xlink:label="loc_us-gaap_OtherComprehensiveIncomeUnrealizedGainLossOnDerivativesArisingDuringPeriodNetOfTax_63FB1A417172E823C129CD2C9681A682" xlink:type="locator"/>
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<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_OtherComprehensiveIncomeLossAmortizationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetPriorServiceCostCreditNetOfTax" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossAmortizationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetPriorServiceCostCreditNetOfTax_AD3481AF8E510A0FDD1CCD2D2384BA08" xlink:type="locator"/>
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<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ComprehensiveIncomeNetOfTax" xlink:label="loc_us-gaap_ComprehensiveIncomeNetOfTax_64B8196F18980A70C9CFCD057C0F358F" xlink:type="locator"/>
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<link:label id="lab_us-gaap_BasisOfAccountingPolicyPolicyTextBlock_39B6DBFD3B070C206F8C99386EDC2D79_terseLabel_en-US" xlink:label="lab_us-gaap_BasisOfAccountingPolicyPolicyTextBlock_39B6DBFD3B070C206F8C99386EDC2D79" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Basis of presentation </link:label>
<link:label id="lab_us-gaap_BasisOfAccountingPolicyPolicyTextBlock_39B6DBFD3B070C206F8C99386EDC2D79_label_en-US" xlink:label="lab_us-gaap_BasisOfAccountingPolicyPolicyTextBlock_39B6DBFD3B070C206F8C99386EDC2D79" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Basis of Accounting, Policy [Policy Text Block] </link:label>
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<link:label id="lab_us-gaap_ConsolidationPolicyTextBlock_0EF64283D2C14D7919FF99386EDC4750_terseLabel_en-US" xlink:label="lab_us-gaap_ConsolidationPolicyTextBlock_0EF64283D2C14D7919FF99386EDC4750" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Principles of consolidation </link:label>
<link:label id="lab_us-gaap_ConsolidationPolicyTextBlock_0EF64283D2C14D7919FF99386EDC4750_label_en-US" xlink:label="lab_us-gaap_ConsolidationPolicyTextBlock_0EF64283D2C14D7919FF99386EDC4750" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Consolidation, Policy [Policy Text Block] </link:label>
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<link:label id="lab_us-gaap_UseOfEstimates_44CCDECDF5A8F0C4DA9199386EDC0854_terseLabel_en-US" xlink:label="lab_us-gaap_UseOfEstimates_44CCDECDF5A8F0C4DA9199386EDC0854" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Use of estimates </link:label>
<link:label id="lab_us-gaap_UseOfEstimates_44CCDECDF5A8F0C4DA9199386EDC0854_label_en-US" xlink:label="lab_us-gaap_UseOfEstimates_44CCDECDF5A8F0C4DA9199386EDC0854" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Use of Estimates, Policy [Policy Text Block] </link:label>
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<link:label id="lab_us-gaap_BusinessCombinationsPolicy_7BDE1901D2DFC7C1160E99386EDCADFF_terseLabel_en-US" xlink:label="lab_us-gaap_BusinessCombinationsPolicy_7BDE1901D2DFC7C1160E99386EDCADFF" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Business Acquisitions </link:label>
<link:label id="lab_us-gaap_BusinessCombinationsPolicy_7BDE1901D2DFC7C1160E99386EDCADFF_label_en-US" xlink:label="lab_us-gaap_BusinessCombinationsPolicy_7BDE1901D2DFC7C1160E99386EDCADFF" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Business Combinations Policy [Policy Text Block] </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_BusinessCombinationsPolicy" xlink:label="loc_us-gaap_BusinessCombinationsPolicy_7BDE1901D2DFC7C1160E99386EDCADFF" xlink:type="locator"/>
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<link:label id="lab_us-gaap_RevenueRecognitionPolicyTextBlock_55C4FA4746984610FFA399386EDC96CD_terseLabel_en-US" xlink:label="lab_us-gaap_RevenueRecognitionPolicyTextBlock_55C4FA4746984610FFA399386EDC96CD" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Revenue Recognition </link:label>
<link:label id="lab_us-gaap_RevenueRecognitionPolicyTextBlock_55C4FA4746984610FFA399386EDC96CD_label_en-US" xlink:label="lab_us-gaap_RevenueRecognitionPolicyTextBlock_55C4FA4746984610FFA399386EDC96CD" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Revenue Recognition, Policy [Policy Text Block] </link:label>
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<link:label id="lab_us-gaap_LoansAndLeasesReceivableAllowanceForLoanLossesPolicy_0548A973AD7D41D1BAF899386EDC94F9_terseLabel_en-US" xlink:label="lab_us-gaap_LoansAndLeasesReceivableAllowanceForLoanLossesPolicy_0548A973AD7D41D1BAF899386EDC94F9" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Allowance for losses </link:label>
<link:label id="lab_us-gaap_LoansAndLeasesReceivableAllowanceForLoanLossesPolicy_0548A973AD7D41D1BAF899386EDC94F9_label_en-US" xlink:label="lab_us-gaap_LoansAndLeasesReceivableAllowanceForLoanLossesPolicy_0548A973AD7D41D1BAF899386EDC94F9" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Loans and Leases Receivable, Allowance for Loan Losses Policy [Policy Text Block] </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_LoansAndLeasesReceivableAllowanceForLoanLossesPolicy" xlink:label="loc_us-gaap_LoansAndLeasesReceivableAllowanceForLoanLossesPolicy_0548A973AD7D41D1BAF899386EDC94F9" xlink:type="locator"/>
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<link:label id="lab_us-gaap_ResearchAndDevelopmentExpensePolicy_E501AD95A6A0E27344BC99386EDC9925_terseLabel_en-US" xlink:label="lab_us-gaap_ResearchAndDevelopmentExpensePolicy_E501AD95A6A0E27344BC99386EDC9925" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Cost of services and product development </link:label>
<link:label id="lab_us-gaap_ResearchAndDevelopmentExpensePolicy_E501AD95A6A0E27344BC99386EDC9925_label_en-US" xlink:label="lab_us-gaap_ResearchAndDevelopmentExpensePolicy_E501AD95A6A0E27344BC99386EDC9925" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Research and Development Expense, Policy [Policy Text Block] </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ResearchAndDevelopmentExpensePolicy" xlink:label="loc_us-gaap_ResearchAndDevelopmentExpensePolicy_E501AD95A6A0E27344BC99386EDC9925" xlink:type="locator"/>
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<link:label id="lab_us-gaap_SellingGeneralAndAdministrativeExpensesPolicyTextBlock_14322627AB7FD02D005099386EDCAEA9_terseLabel_en-US" xlink:label="lab_us-gaap_SellingGeneralAndAdministrativeExpensesPolicyTextBlock_14322627AB7FD02D005099386EDCAEA9" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Selling, general and administrative </link:label>
<link:label id="lab_us-gaap_SellingGeneralAndAdministrativeExpensesPolicyTextBlock_14322627AB7FD02D005099386EDCAEA9_label_en-US" xlink:label="lab_us-gaap_SellingGeneralAndAdministrativeExpensesPolicyTextBlock_14322627AB7FD02D005099386EDCAEA9" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Selling, General and Administrative Expenses, Policy [Policy Text Block] </link:label>
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<link:label id="lab_us-gaap_CommissionsExpensePolicyPolicyTextBlock_6DE8FD0EDE81DAE86F1C99386EDCE755_terseLabel_en-US" xlink:label="lab_us-gaap_CommissionsExpensePolicyPolicyTextBlock_6DE8FD0EDE81DAE86F1C99386EDCE755" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Commissions expense </link:label>
<link:label id="lab_us-gaap_CommissionsExpensePolicyPolicyTextBlock_6DE8FD0EDE81DAE86F1C99386EDCE755_label_en-US" xlink:label="lab_us-gaap_CommissionsExpensePolicyPolicyTextBlock_6DE8FD0EDE81DAE86F1C99386EDCE755" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Commissions Expense, Policy [Policy Text Block] </link:label>
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<link:label id="lab_us-gaap_ShareBasedCompensationOptionAndIncentivePlansPolicy_D3666485EFD0BEA8260E99386EDD5B13_terseLabel_en-US" xlink:label="lab_us-gaap_ShareBasedCompensationOptionAndIncentivePlansPolicy_D3666485EFD0BEA8260E99386EDD5B13" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Stock-based compensation expense </link:label>
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<link:label id="lab_us-gaap_IncomeTaxPolicyTextBlock_4D0C629EC01A69961B8199386EDD1ECA_terseLabel_en-US" xlink:label="lab_us-gaap_IncomeTaxPolicyTextBlock_4D0C629EC01A69961B8199386EDD1ECA" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Income tax expense </link:label>
<link:label id="lab_us-gaap_IncomeTaxPolicyTextBlock_4D0C629EC01A69961B8199386EDD1ECA_label_en-US" xlink:label="lab_us-gaap_IncomeTaxPolicyTextBlock_4D0C629EC01A69961B8199386EDD1ECA" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Income Tax, Policy [Policy Text Block] </link:label>
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<link:label id="lab_us-gaap_CashAndCashEquivalentsPolicyTextBlock_30A4D3F6F8197C936CA499386EDD8838_terseLabel_en-US" xlink:label="lab_us-gaap_CashAndCashEquivalentsPolicyTextBlock_30A4D3F6F8197C936CA499386EDD8838" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Cash and cash equivalents </link:label>
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<link:label id="lab_us-gaap_PropertyPlantAndEquipmentPolicyTextBlock_EFD36F239637BBA8882999386EDDC58A_terseLabel_en-US" xlink:label="lab_us-gaap_PropertyPlantAndEquipmentPolicyTextBlock_EFD36F239637BBA8882999386EDDC58A" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Property, equipment and leasehold improvements </link:label>
<link:label id="lab_us-gaap_PropertyPlantAndEquipmentPolicyTextBlock_EFD36F239637BBA8882999386EDDC58A_label_en-US" xlink:label="lab_us-gaap_PropertyPlantAndEquipmentPolicyTextBlock_EFD36F239637BBA8882999386EDDC58A" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Property, Plant and Equipment, Policy [Policy Text Block] </link:label>
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<link:label id="lab_us-gaap_GoodwillAndIntangibleAssetsIntangibleAssetsPolicy_AC3D1C63FE286AF92FAC99386EDD9FB2_terseLabel_en-US" xlink:label="lab_us-gaap_GoodwillAndIntangibleAssetsIntangibleAssetsPolicy_AC3D1C63FE286AF92FAC99386EDD9FB2" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Intangible assets </link:label>
<link:label id="lab_us-gaap_GoodwillAndIntangibleAssetsIntangibleAssetsPolicy_AC3D1C63FE286AF92FAC99386EDD9FB2_label_en-US" xlink:label="lab_us-gaap_GoodwillAndIntangibleAssetsIntangibleAssetsPolicy_AC3D1C63FE286AF92FAC99386EDD9FB2" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Goodwill and Intangible Assets, Intangible Assets, Policy [Policy Text Block] </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_GoodwillAndIntangibleAssetsIntangibleAssetsPolicy" xlink:label="loc_us-gaap_GoodwillAndIntangibleAssetsIntangibleAssetsPolicy_AC3D1C63FE286AF92FAC99386EDD9FB2" xlink:type="locator"/>
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<link:label id="lab_us-gaap_GoodwillAndIntangibleAssetsGoodwillPolicy_B5B41A2337615085E9EC99386EDD1461_terseLabel_en-US" xlink:label="lab_us-gaap_GoodwillAndIntangibleAssetsGoodwillPolicy_B5B41A2337615085E9EC99386EDD1461" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Goodwill </link:label>
<link:label id="lab_us-gaap_GoodwillAndIntangibleAssetsGoodwillPolicy_B5B41A2337615085E9EC99386EDD1461_label_en-US" xlink:label="lab_us-gaap_GoodwillAndIntangibleAssetsGoodwillPolicy_B5B41A2337615085E9EC99386EDD1461" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Goodwill and Intangible Assets, Goodwill, Policy [Policy Text Block] </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_GoodwillAndIntangibleAssetsGoodwillPolicy" xlink:label="loc_us-gaap_GoodwillAndIntangibleAssetsGoodwillPolicy_B5B41A2337615085E9EC99386EDD1461" xlink:type="locator"/>
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<link:label id="lab_us-gaap_ImpairmentOrDisposalOfLongLivedAssetsPolicyTextBlock_B803DE3B056867C49BA899386EDD059C_terseLabel_en-US" xlink:label="lab_us-gaap_ImpairmentOrDisposalOfLongLivedAssetsPolicyTextBlock_B803DE3B056867C49BA899386EDD059C" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Impairment of long-lived assets </link:label>
<link:label id="lab_us-gaap_ImpairmentOrDisposalOfLongLivedAssetsPolicyTextBlock_B803DE3B056867C49BA899386EDD059C_label_en-US" xlink:label="lab_us-gaap_ImpairmentOrDisposalOfLongLivedAssetsPolicyTextBlock_B803DE3B056867C49BA899386EDD059C" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Impairment or Disposal of Long-Lived Assets, Policy [Policy Text Block] </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ImpairmentOrDisposalOfLongLivedAssetsPolicyTextBlock" xlink:label="loc_us-gaap_ImpairmentOrDisposalOfLongLivedAssetsPolicyTextBlock_B803DE3B056867C49BA899386EDD059C" xlink:type="locator"/>
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<link:label id="lab_us-gaap_PensionAndOtherPostretirementPlansPolicy_2352F5280CC47209048099386EDDD5A1_terseLabel_en-US" xlink:label="lab_us-gaap_PensionAndOtherPostretirementPlansPolicy_2352F5280CC47209048099386EDDD5A1" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Pension obligations </link:label>
<link:label id="lab_us-gaap_PensionAndOtherPostretirementPlansPolicy_2352F5280CC47209048099386EDDD5A1_label_en-US" xlink:label="lab_us-gaap_PensionAndOtherPostretirementPlansPolicy_2352F5280CC47209048099386EDDD5A1" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Pension and Other Postretirement Plans, Policy [Policy Text Block] </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_PensionAndOtherPostretirementPlansPolicy" xlink:label="loc_us-gaap_PensionAndOtherPostretirementPlansPolicy_2352F5280CC47209048099386EDDD5A1" xlink:type="locator"/>
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<link:label id="lab_us-gaap_DebtPolicyTextBlock_61A4453F219409C64D0999386EDD4292_terseLabel_en-US" xlink:label="lab_us-gaap_DebtPolicyTextBlock_61A4453F219409C64D0999386EDD4292" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Debt </link:label>
<link:label id="lab_us-gaap_DebtPolicyTextBlock_61A4453F219409C64D0999386EDD4292_label_en-US" xlink:label="lab_us-gaap_DebtPolicyTextBlock_61A4453F219409C64D0999386EDD4292" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Debt, Policy [Policy Text Block] </link:label>
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<link:label id="lab_us-gaap_ForeignCurrencyTransactionsAndTranslationsPolicyTextBlock_0D8DFFAF277B54215AC899386EDDE243_terseLabel_en-US" xlink:label="lab_us-gaap_ForeignCurrencyTransactionsAndTranslationsPolicyTextBlock_0D8DFFAF277B54215AC899386EDDE243" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Foreign currency exposure </link:label>
<link:label id="lab_us-gaap_ForeignCurrencyTransactionsAndTranslationsPolicyTextBlock_0D8DFFAF277B54215AC899386EDDE243_label_en-US" xlink:label="lab_us-gaap_ForeignCurrencyTransactionsAndTranslationsPolicyTextBlock_0D8DFFAF277B54215AC899386EDDE243" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Foreign Currency Transactions and Translations Policy [Policy Text Block] </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ForeignCurrencyTransactionsAndTranslationsPolicyTextBlock" xlink:label="loc_us-gaap_ForeignCurrencyTransactionsAndTranslationsPolicyTextBlock_0D8DFFAF277B54215AC899386EDDE243" xlink:type="locator"/>
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<link:label id="lab_us-gaap_ComprehensiveIncomePolicyPolicyTextBlock_9AE00A93C76AF53B956C99386EDD7C44_terseLabel_en-US" xlink:label="lab_us-gaap_ComprehensiveIncomePolicyPolicyTextBlock_9AE00A93C76AF53B956C99386EDD7C44" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Comprehensive income </link:label>
<link:label id="lab_us-gaap_ComprehensiveIncomePolicyPolicyTextBlock_9AE00A93C76AF53B956C99386EDD7C44_label_en-US" xlink:label="lab_us-gaap_ComprehensiveIncomePolicyPolicyTextBlock_9AE00A93C76AF53B956C99386EDD7C44" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Comprehensive Income, Policy [Policy Text Block] </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ComprehensiveIncomePolicyPolicyTextBlock" xlink:label="loc_us-gaap_ComprehensiveIncomePolicyPolicyTextBlock_9AE00A93C76AF53B956C99386EDD7C44" xlink:type="locator"/>
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<link:label id="lab_us-gaap_FairValueOfFinancialInstrumentsPolicy_CC01E07CBBBCFE1F99D599386EDD1F26_terseLabel_en-US" xlink:label="lab_us-gaap_FairValueOfFinancialInstrumentsPolicy_CC01E07CBBBCFE1F99D599386EDD1F26" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Fair value disclosures </link:label>
<link:label id="lab_us-gaap_FairValueOfFinancialInstrumentsPolicy_CC01E07CBBBCFE1F99D599386EDD1F26_label_en-US" xlink:label="lab_us-gaap_FairValueOfFinancialInstrumentsPolicy_CC01E07CBBBCFE1F99D599386EDD1F26" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Fair Value of Financial Instruments, Policy [Policy Text Block] </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_FairValueOfFinancialInstrumentsPolicy" xlink:label="loc_us-gaap_FairValueOfFinancialInstrumentsPolicy_CC01E07CBBBCFE1F99D599386EDD1F26" xlink:type="locator"/>
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<link:label id="lab_us-gaap_ConcentrationRiskCreditRisk_E8758BCAF81B6BB22F8999386EDD3E09_terseLabel_en-US" xlink:label="lab_us-gaap_ConcentrationRiskCreditRisk_E8758BCAF81B6BB22F8999386EDD3E09" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Concentrations of credit risk </link:label>
<link:label id="lab_us-gaap_ConcentrationRiskCreditRisk_E8758BCAF81B6BB22F8999386EDD3E09_label_en-US" xlink:label="lab_us-gaap_ConcentrationRiskCreditRisk_E8758BCAF81B6BB22F8999386EDD3E09" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Concentration Risk, Credit Risk, Policy [Policy Text Block] </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ConcentrationRiskCreditRisk" xlink:label="loc_us-gaap_ConcentrationRiskCreditRisk_E8758BCAF81B6BB22F8999386EDD3E09" xlink:type="locator"/>
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<link:label id="lab_us-gaap_RepurchaseAndResaleAgreementsPolicy_F5667ECEFBA23117A69B99386EDDFBD9_terseLabel_en-US" xlink:label="lab_us-gaap_RepurchaseAndResaleAgreementsPolicy_F5667ECEFBA23117A69B99386EDDFBD9" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Stock repurchase programs </link:label>
<link:label id="lab_us-gaap_RepurchaseAndResaleAgreementsPolicy_F5667ECEFBA23117A69B99386EDDFBD9_label_en-US" xlink:label="lab_us-gaap_RepurchaseAndResaleAgreementsPolicy_F5667ECEFBA23117A69B99386EDDFBD9" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Repurchase and Resale Agreements Policy [Policy Text Block] </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_RepurchaseAndResaleAgreementsPolicy" xlink:label="loc_us-gaap_RepurchaseAndResaleAgreementsPolicy_F5667ECEFBA23117A69B99386EDDFBD9" xlink:type="locator"/>
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<link:label id="lab_us-gaap_NewAccountingPronouncementsPolicyPolicyTextBlock_3C2B16406D1DD2F92CE499386EDDC9C2_terseLabel_en-US" xlink:label="lab_us-gaap_NewAccountingPronouncementsPolicyPolicyTextBlock_3C2B16406D1DD2F92CE499386EDDC9C2" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Adoption of new accounting standards and Accounting standards issued but not yet adopted </link:label>
<link:label id="lab_us-gaap_NewAccountingPronouncementsPolicyPolicyTextBlock_3C2B16406D1DD2F92CE499386EDDC9C2_label_en-US" xlink:label="lab_us-gaap_NewAccountingPronouncementsPolicyPolicyTextBlock_3C2B16406D1DD2F92CE499386EDDC9C2" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> New Accounting Pronouncements, Policy [Policy Text Block] </link:label>
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<link:label id="lab_us-gaap_StatementOfFinancialPositionAbstract_09B05EF7EE1328F1EE0EB3EC02A4D47B_label_en-US" xlink:label="lab_us-gaap_StatementOfFinancialPositionAbstract_09B05EF7EE1328F1EE0EB3EC02A4D47B" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Statement of Financial Position [Abstract] </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_StatementOfFinancialPositionAbstract" xlink:label="loc_us-gaap_StatementOfFinancialPositionAbstract_09B05EF7EE1328F1EE0EB3EC02A4D47B" xlink:type="locator"/>
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<link:label id="lab_us-gaap_AllowanceForDoubtfulAccountsReceivableCurrent_86469C40E51BB4BD7AF0B3EC02A5BCA0_terseLabel_en-US" xlink:label="lab_us-gaap_AllowanceForDoubtfulAccountsReceivableCurrent_86469C40E51BB4BD7AF0B3EC02A5BCA0" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Fees receivable, allowances </link:label>
<link:label id="lab_us-gaap_AllowanceForDoubtfulAccountsReceivableCurrent_86469C40E51BB4BD7AF0B3EC02A5BCA0_label_en-US" xlink:label="lab_us-gaap_AllowanceForDoubtfulAccountsReceivableCurrent_86469C40E51BB4BD7AF0B3EC02A5BCA0" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Allowance for Doubtful Accounts Receivable, Current </link:label>
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<link:label id="lab_us-gaap_PreferredStockParOrStatedValuePerShare_4289D16C20D7948EE576B3EC02A5FE83_terseLabel_en-US" xlink:label="lab_us-gaap_PreferredStockParOrStatedValuePerShare_4289D16C20D7948EE576B3EC02A5FE83" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Preferred stock par value (in Dollars per share) </link:label>
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<link:label id="lab_us-gaap_PreferredStockSharesAuthorized_21ECD54FAFE52933A0F6B3EC02A5BD25_terseLabel_en-US" xlink:label="lab_us-gaap_PreferredStockSharesAuthorized_21ECD54FAFE52933A0F6B3EC02A5BD25" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Preferred stock, shares authorized </link:label>
<link:label id="lab_us-gaap_PreferredStockSharesAuthorized_21ECD54FAFE52933A0F6B3EC02A5BD25_label_en-US" xlink:label="lab_us-gaap_PreferredStockSharesAuthorized_21ECD54FAFE52933A0F6B3EC02A5BD25" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Preferred Stock, Shares Authorized </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_PreferredStockSharesAuthorized" xlink:label="loc_us-gaap_PreferredStockSharesAuthorized_21ECD54FAFE52933A0F6B3EC02A5BD25" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_PreferredStockSharesAuthorized_21ECD54FAFE52933A0F6B3EC02A5BD25" xlink:to="lab_us-gaap_PreferredStockSharesAuthorized_21ECD54FAFE52933A0F6B3EC02A5BD25" xlink:type="arc"/>
<link:label id="lab_us-gaap_PreferredStockSharesIssued_1FCFD51B478DFEA8E7EFB3EC02A5A053_terseLabel_en-US" xlink:label="lab_us-gaap_PreferredStockSharesIssued_1FCFD51B478DFEA8E7EFB3EC02A5A053" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Preferred stock, shares issued </link:label>
<link:label id="lab_us-gaap_PreferredStockSharesIssued_1FCFD51B478DFEA8E7EFB3EC02A5A053_label_en-US" xlink:label="lab_us-gaap_PreferredStockSharesIssued_1FCFD51B478DFEA8E7EFB3EC02A5A053" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Preferred Stock, Shares Issued </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_PreferredStockSharesIssued" xlink:label="loc_us-gaap_PreferredStockSharesIssued_1FCFD51B478DFEA8E7EFB3EC02A5A053" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_PreferredStockSharesIssued_1FCFD51B478DFEA8E7EFB3EC02A5A053" xlink:to="lab_us-gaap_PreferredStockSharesIssued_1FCFD51B478DFEA8E7EFB3EC02A5A053" xlink:type="arc"/>
<link:label id="lab_us-gaap_PreferredStockSharesOutstanding_D771C8E2D29EB472415BB3EC02A5E403_terseLabel_en-US" xlink:label="lab_us-gaap_PreferredStockSharesOutstanding_D771C8E2D29EB472415BB3EC02A5E403" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Preferred stock, shares outstanding </link:label>
<link:label id="lab_us-gaap_PreferredStockSharesOutstanding_D771C8E2D29EB472415BB3EC02A5E403_label_en-US" xlink:label="lab_us-gaap_PreferredStockSharesOutstanding_D771C8E2D29EB472415BB3EC02A5E403" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Preferred Stock, Shares Outstanding </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_PreferredStockSharesOutstanding" xlink:label="loc_us-gaap_PreferredStockSharesOutstanding_D771C8E2D29EB472415BB3EC02A5E403" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_PreferredStockSharesOutstanding_D771C8E2D29EB472415BB3EC02A5E403" xlink:to="lab_us-gaap_PreferredStockSharesOutstanding_D771C8E2D29EB472415BB3EC02A5E403" xlink:type="arc"/>
<link:label id="lab_us-gaap_CommonStockParOrStatedValuePerShare_D69D13847784A7BCF90BB3EC02A5484F_terseLabel_en-US" xlink:label="lab_us-gaap_CommonStockParOrStatedValuePerShare_D69D13847784A7BCF90BB3EC02A5484F" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Common stock par value (in Dollars per share) </link:label>
<link:label id="lab_us-gaap_CommonStockParOrStatedValuePerShare_D69D13847784A7BCF90BB3EC02A5484F_label_en-US" xlink:label="lab_us-gaap_CommonStockParOrStatedValuePerShare_D69D13847784A7BCF90BB3EC02A5484F" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Common Stock, Par or Stated Value Per Share </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_CommonStockParOrStatedValuePerShare" xlink:label="loc_us-gaap_CommonStockParOrStatedValuePerShare_D69D13847784A7BCF90BB3EC02A5484F" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_CommonStockParOrStatedValuePerShare_D69D13847784A7BCF90BB3EC02A5484F" xlink:to="lab_us-gaap_CommonStockParOrStatedValuePerShare_D69D13847784A7BCF90BB3EC02A5484F" xlink:type="arc"/>
<link:label id="lab_us-gaap_CommonStockSharesAuthorized_160934DB1F9246C6AA8DB3EC02A57BC1_terseLabel_en-US" xlink:label="lab_us-gaap_CommonStockSharesAuthorized_160934DB1F9246C6AA8DB3EC02A57BC1" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Common stock, shares authorized </link:label>
<link:label id="lab_us-gaap_CommonStockSharesAuthorized_160934DB1F9246C6AA8DB3EC02A57BC1_label_en-US" xlink:label="lab_us-gaap_CommonStockSharesAuthorized_160934DB1F9246C6AA8DB3EC02A57BC1" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Common Stock, Shares Authorized </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_CommonStockSharesAuthorized" xlink:label="loc_us-gaap_CommonStockSharesAuthorized_160934DB1F9246C6AA8DB3EC02A57BC1" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_CommonStockSharesAuthorized_160934DB1F9246C6AA8DB3EC02A57BC1" xlink:to="lab_us-gaap_CommonStockSharesAuthorized_160934DB1F9246C6AA8DB3EC02A57BC1" xlink:type="arc"/>
<link:label id="lab_us-gaap_CommonStockSharesIssued_4907573D5AF674AADACFB3EC02A5E798_terseLabel_en-US" xlink:label="lab_us-gaap_CommonStockSharesIssued_4907573D5AF674AADACFB3EC02A5E798" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Common stock, shares issued </link:label>
<link:label id="lab_us-gaap_CommonStockSharesIssued_4907573D5AF674AADACFB3EC02A5E798_label_en-US" xlink:label="lab_us-gaap_CommonStockSharesIssued_4907573D5AF674AADACFB3EC02A5E798" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Common Stock, Shares, Issued </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_CommonStockSharesIssued" xlink:label="loc_us-gaap_CommonStockSharesIssued_4907573D5AF674AADACFB3EC02A5E798" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_CommonStockSharesIssued_4907573D5AF674AADACFB3EC02A5E798" xlink:to="lab_us-gaap_CommonStockSharesIssued_4907573D5AF674AADACFB3EC02A5E798" xlink:type="arc"/>
<link:label id="lab_us-gaap_TreasuryStockShares_E94765F03CE16804D6AAB3EC02A5D668_terseLabel_en-US" xlink:label="lab_us-gaap_TreasuryStockShares_E94765F03CE16804D6AAB3EC02A5D668" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Treasury stock, Shares </link:label>
<link:label id="lab_us-gaap_TreasuryStockShares_E94765F03CE16804D6AAB3EC02A5D668_label_en-US" xlink:label="lab_us-gaap_TreasuryStockShares_E94765F03CE16804D6AAB3EC02A5D668" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Treasury Stock, Shares </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_TreasuryStockShares" xlink:label="loc_us-gaap_TreasuryStockShares_E94765F03CE16804D6AAB3EC02A5D668" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_TreasuryStockShares_E94765F03CE16804D6AAB3EC02A5D668" xlink:to="lab_us-gaap_TreasuryStockShares_E94765F03CE16804D6AAB3EC02A5D668" xlink:type="arc"/>
<link:label id="lab_us-gaap_ScheduleOfStockByClassTable_73F085A809E501BDDE69E53BFB8210A7_terseLabel_en-US" xlink:label="lab_us-gaap_ScheduleOfStockByClassTable_73F085A809E501BDDE69E53BFB8210A7" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Schedule of Stock by Class [Table] </link:label>
<link:label id="lab_us-gaap_ScheduleOfStockByClassTable_73F085A809E501BDDE69E53BFB8210A7_label_en-US" xlink:label="lab_us-gaap_ScheduleOfStockByClassTable_73F085A809E501BDDE69E53BFB8210A7" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Schedule of Stock by Class [Table] </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ScheduleOfStockByClassTable" xlink:label="loc_us-gaap_ScheduleOfStockByClassTable_73F085A809E501BDDE69E53BFB8210A7" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ScheduleOfStockByClassTable_73F085A809E501BDDE69E53BFB8210A7" xlink:to="lab_us-gaap_ScheduleOfStockByClassTable_73F085A809E501BDDE69E53BFB8210A7" xlink:type="arc"/>
<link:label id="lab_us-gaap_StatementClassOfStockAxis_F84AFB82C8D9625F148FE53BFB83EC57_terseLabel_en-US" xlink:label="lab_us-gaap_StatementClassOfStockAxis_F84AFB82C8D9625F148FE53BFB83EC57" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Class of Stock [Axis] </link:label>
<link:label id="lab_us-gaap_StatementClassOfStockAxis_F84AFB82C8D9625F148FE53BFB83EC57_label_en-US" xlink:label="lab_us-gaap_StatementClassOfStockAxis_F84AFB82C8D9625F148FE53BFB83EC57" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Class of Stock [Axis] </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_StatementClassOfStockAxis" xlink:label="loc_us-gaap_StatementClassOfStockAxis_F84AFB82C8D9625F148FE53BFB83EC57" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_StatementClassOfStockAxis_F84AFB82C8D9625F148FE53BFB83EC57" xlink:to="lab_us-gaap_StatementClassOfStockAxis_F84AFB82C8D9625F148FE53BFB83EC57" xlink:type="arc"/>
<link:label id="lab_us-gaap_ClassOfStockDomain_06BEC8A58EB6212DC5D7E53BFB83F624_terseLabel_en-US" xlink:label="lab_us-gaap_ClassOfStockDomain_06BEC8A58EB6212DC5D7E53BFB83F624" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Class of Stock [Domain] </link:label>
<link:label id="lab_us-gaap_ClassOfStockDomain_06BEC8A58EB6212DC5D7E53BFB83F624_label_en-US" xlink:label="lab_us-gaap_ClassOfStockDomain_06BEC8A58EB6212DC5D7E53BFB83F624" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Class of Stock [Domain] </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ClassOfStockDomain" xlink:label="loc_us-gaap_ClassOfStockDomain_06BEC8A58EB6212DC5D7E53BFB83F624" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ClassOfStockDomain_06BEC8A58EB6212DC5D7E53BFB83F624" xlink:to="lab_us-gaap_ClassOfStockDomain_06BEC8A58EB6212DC5D7E53BFB83F624" xlink:type="arc"/>
<link:label id="lab_it_CommonStockEquivalentsMember_09C917AEC9689BC93396E53BFB83702F_terseLabel_en-US" xlink:label="lab_it_CommonStockEquivalentsMember_09C917AEC9689BC93396E53BFB83702F" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Common Stock Equivalents (CSEs) </link:label>
<link:label id="lab_it_CommonStockEquivalentsMember_09C917AEC9689BC93396E53BFB83702F_label_en-US" xlink:label="lab_it_CommonStockEquivalentsMember_09C917AEC9689BC93396E53BFB83702F" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Common Stock Equivalents [Member] </link:label>
<link:label id="lab_it_CommonStockEquivalentsMember_09C917AEC9689BC93396E53BFB83702F_documentation_en-US" xlink:label="lab_it_CommonStockEquivalentsMember_09C917AEC9689BC93396E53BFB83702F" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US"> -- None. No documentation exists for this element. -- </link:label>
<link:loc xlink:href="it-20161231.xsd#it_CommonStockEquivalentsMember" xlink:label="loc_it_CommonStockEquivalentsMember_09C917AEC9689BC93396E53BFB83702F" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_it_CommonStockEquivalentsMember_09C917AEC9689BC93396E53BFB83702F" xlink:to="lab_it_CommonStockEquivalentsMember_09C917AEC9689BC93396E53BFB83702F" xlink:type="arc"/>
<link:label id="lab_us-gaap_ClassOfStockLineItems_72C6A98BAF669371E5E6E53BFB832401_terseLabel_en-US" xlink:label="lab_us-gaap_ClassOfStockLineItems_72C6A98BAF669371E5E6E53BFB832401" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Class of Stock [Line Items] </link:label>
<link:label id="lab_us-gaap_ClassOfStockLineItems_72C6A98BAF669371E5E6E53BFB832401_label_en-US" xlink:label="lab_us-gaap_ClassOfStockLineItems_72C6A98BAF669371E5E6E53BFB832401" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Class of Stock [Line Items] </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ClassOfStockLineItems" xlink:label="loc_us-gaap_ClassOfStockLineItems_72C6A98BAF669371E5E6E53BFB832401" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ClassOfStockLineItems_72C6A98BAF669371E5E6E53BFB832401" xlink:to="lab_us-gaap_ClassOfStockLineItems_72C6A98BAF669371E5E6E53BFB832401" xlink:type="arc"/>
<link:label id="lab_us-gaap_StockRepurchasedDuringPeriodShares_BA6161329679C3EDE92FE53BFB830119_terseLabel_en-US" xlink:label="lab_us-gaap_StockRepurchasedDuringPeriodShares_BA6161329679C3EDE92FE53BFB830119" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Stock repurchased during period (in shares) </link:label>
<link:label id="lab_us-gaap_StockRepurchasedDuringPeriodShares_BA6161329679C3EDE92FE53BFB830119_label_en-US" xlink:label="lab_us-gaap_StockRepurchasedDuringPeriodShares_BA6161329679C3EDE92FE53BFB830119" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Stock Repurchased During Period, Shares </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_StockRepurchasedDuringPeriodShares" xlink:label="loc_us-gaap_StockRepurchasedDuringPeriodShares_BA6161329679C3EDE92FE53BFB830119" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_StockRepurchasedDuringPeriodShares_BA6161329679C3EDE92FE53BFB830119" xlink:to="lab_us-gaap_StockRepurchasedDuringPeriodShares_BA6161329679C3EDE92FE53BFB830119" xlink:type="arc"/>
<link:label id="lab_us-gaap_ValuationAndQualifyingAccountsAbstract_D92D481B069426E67BC0E53BFC6FC0EA_label_en-US" xlink:label="lab_us-gaap_ValuationAndQualifyingAccountsAbstract_D92D481B069426E67BC0E53BFC6FC0EA" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Valuation and Qualifying Accounts [Abstract] </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ValuationAndQualifyingAccountsAbstract" xlink:label="loc_us-gaap_ValuationAndQualifyingAccountsAbstract_D92D481B069426E67BC0E53BFC6FC0EA" xlink:type="locator"/>
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<link:label id="lab_us-gaap_MovementInValuationAllowancesAndReservesRollForward_267E2A9E27CAE57FBCE7E53BFC6F2F66_terseLabel_en-US" xlink:label="lab_us-gaap_MovementInValuationAllowancesAndReservesRollForward_267E2A9E27CAE57FBCE7E53BFC6F2F66" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Movement in Valuation Allowances and Reserves [Roll Forward] </link:label>
<link:label id="lab_us-gaap_MovementInValuationAllowancesAndReservesRollForward_267E2A9E27CAE57FBCE7E53BFC6F2F66_label_en-US" xlink:label="lab_us-gaap_MovementInValuationAllowancesAndReservesRollForward_267E2A9E27CAE57FBCE7E53BFC6F2F66" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Movement in Valuation Allowances and Reserves [Roll Forward] </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_MovementInValuationAllowancesAndReservesRollForward" xlink:label="loc_us-gaap_MovementInValuationAllowancesAndReservesRollForward_267E2A9E27CAE57FBCE7E53BFC6F2F66" xlink:type="locator"/>
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<link:label id="lab_us-gaap_ValuationAllowancesAndReservesBalance_8FF68D670B00026A4FFCE53BFC6FF443_periodStartLabel_en-US" xlink:label="lab_us-gaap_ValuationAllowancesAndReservesBalance_8FF68D670B00026A4FFCE53BFC6FF443" xlink:role="http://www.xbrl.org/2003/role/periodStartLabel" xlink:type="resource" xml:lang="en-US"> Balance at Beginning of Year </link:label>
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<link:label id="lab_us-gaap_DefinedBenefitPlanServiceCost_8C32D3886D1F11C8D956B3EC00AA5CC1_label_en-US" xlink:label="lab_us-gaap_DefinedBenefitPlanServiceCost_8C32D3886D1F11C8D956B3EC00AA5CC1" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Defined Benefit Plan, Service Cost </link:label>
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<link:label id="lab_us-gaap_DefinedBenefitPlanInterestCost_A74B1757E776159F58E1B3EC00AA608D_label_en-US" xlink:label="lab_us-gaap_DefinedBenefitPlanInterestCost_A74B1757E776159F58E1B3EC00AA608D" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Defined Benefit Plan, Interest Cost </link:label>
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<link:label id="lab_us-gaap_DefinedBenefitPlanExpectedReturnOnPlanAssets_B0C9D2393911B8014A1AB3EC00AAEAAD_negatedLabel_en-US" xlink:label="lab_us-gaap_DefinedBenefitPlanExpectedReturnOnPlanAssets_B0C9D2393911B8014A1AB3EC00AAEAAD" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:type="resource" xml:lang="en-US"> Expected return on plan assets </link:label>
<link:label id="lab_us-gaap_DefinedBenefitPlanExpectedReturnOnPlanAssets_B0C9D2393911B8014A1AB3EC00AAEAAD_label_en-US" xlink:label="lab_us-gaap_DefinedBenefitPlanExpectedReturnOnPlanAssets_B0C9D2393911B8014A1AB3EC00AAEAAD" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Defined Benefit Plan, Expected Return on Plan Assets </link:label>
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<link:label id="lab_us-gaap_AssetsAbstract_94493E33807242A1CAEF3E9437258EFA_terseLabel_en-US" xlink:label="lab_us-gaap_AssetsAbstract_94493E33807242A1CAEF3E9437258EFA" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> ASSETS </link:label>
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<link:label id="lab_us-gaap_CashAndCashEquivalentsAtCarryingValue_9A5B6ED915F9DF40F93C3E9437259D3B_terseLabel_en-US" xlink:label="lab_us-gaap_CashAndCashEquivalentsAtCarryingValue_9A5B6ED915F9DF40F93C3E9437259D3B" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Cash and cash equivalents </link:label>
<link:label id="lab_us-gaap_CashAndCashEquivalentsAtCarryingValue_9A5B6ED915F9DF40F93C3E9437259D3B_label_en-US" xlink:label="lab_us-gaap_CashAndCashEquivalentsAtCarryingValue_9A5B6ED915F9DF40F93C3E9437259D3B" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Cash and Cash Equivalents, at Carrying Value </link:label>
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<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_CashAndCashEquivalentsAtCarryingValue_9A5B6ED915F9DF40F93C3E9437259D3B" xlink:to="lab_us-gaap_CashAndCashEquivalentsAtCarryingValue_9A5B6ED915F9DF40F93C3E9437259D3B" xlink:type="arc"/>
<link:label id="lab_us-gaap_AccountsReceivableNetCurrent_957C11314740C3FC22AE3E943726056E_terseLabel_en-US" xlink:label="lab_us-gaap_AccountsReceivableNetCurrent_957C11314740C3FC22AE3E943726056E" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Fees receivable, net of allowances of $7,400 and $6,900 respectively </link:label>
<link:label id="lab_us-gaap_AccountsReceivableNetCurrent_957C11314740C3FC22AE3E943726056E_label_en-US" xlink:label="lab_us-gaap_AccountsReceivableNetCurrent_957C11314740C3FC22AE3E943726056E" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Accounts Receivable, Net, Current </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_AccountsReceivableNetCurrent" xlink:label="loc_us-gaap_AccountsReceivableNetCurrent_957C11314740C3FC22AE3E943726056E" xlink:type="locator"/>
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<link:label id="lab_us-gaap_OtherDeferredCostsNet_179D79ACDA6FE7B9C4EF3E9437264E0B_terseLabel_en-US" xlink:label="lab_us-gaap_OtherDeferredCostsNet_179D79ACDA6FE7B9C4EF3E9437264E0B" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Deferred commissions </link:label>
<link:label id="lab_us-gaap_OtherDeferredCostsNet_179D79ACDA6FE7B9C4EF3E9437264E0B_label_en-US" xlink:label="lab_us-gaap_OtherDeferredCostsNet_179D79ACDA6FE7B9C4EF3E9437264E0B" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Other Deferred Costs, Net </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_OtherDeferredCostsNet" xlink:label="loc_us-gaap_OtherDeferredCostsNet_179D79ACDA6FE7B9C4EF3E9437264E0B" xlink:type="locator"/>
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<link:label id="lab_us-gaap_PrepaidExpenseAndOtherAssetsCurrent_69396BFF23F00C5D8C443E943726C780_terseLabel_en-US" xlink:label="lab_us-gaap_PrepaidExpenseAndOtherAssetsCurrent_69396BFF23F00C5D8C443E943726C780" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Prepaid expenses and other current assets </link:label>
<link:label id="lab_us-gaap_PrepaidExpenseAndOtherAssetsCurrent_69396BFF23F00C5D8C443E943726C780_label_en-US" xlink:label="lab_us-gaap_PrepaidExpenseAndOtherAssetsCurrent_69396BFF23F00C5D8C443E943726C780" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Prepaid Expense and Other Assets, Current </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_PrepaidExpenseAndOtherAssetsCurrent" xlink:label="loc_us-gaap_PrepaidExpenseAndOtherAssetsCurrent_69396BFF23F00C5D8C443E943726C780" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_PrepaidExpenseAndOtherAssetsCurrent_69396BFF23F00C5D8C443E943726C780" xlink:to="lab_us-gaap_PrepaidExpenseAndOtherAssetsCurrent_69396BFF23F00C5D8C443E943726C780" xlink:type="arc"/>
<link:label id="lab_us-gaap_AssetsCurrent_DD5683EF9AA7A63482793E94372623AE_totalLabel_en-US" xlink:label="lab_us-gaap_AssetsCurrent_DD5683EF9AA7A63482793E94372623AE" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:type="resource" xml:lang="en-US"> Total current assets </link:label>
<link:label id="lab_us-gaap_AssetsCurrent_DD5683EF9AA7A63482793E94372623AE_label_en-US" xlink:label="lab_us-gaap_AssetsCurrent_DD5683EF9AA7A63482793E94372623AE" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Assets, Current </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_AssetsCurrent" xlink:label="loc_us-gaap_AssetsCurrent_DD5683EF9AA7A63482793E94372623AE" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_AssetsCurrent_DD5683EF9AA7A63482793E94372623AE" xlink:to="lab_us-gaap_AssetsCurrent_DD5683EF9AA7A63482793E94372623AE" xlink:type="arc"/>
<link:label id="lab_us-gaap_PropertyPlantAndEquipmentNet_12AC436CBECD7734DC933E943726363C_terseLabel_en-US" xlink:label="lab_us-gaap_PropertyPlantAndEquipmentNet_12AC436CBECD7734DC933E943726363C" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Property, equipment and leasehold improvements, net </link:label>
<link:label id="lab_us-gaap_PropertyPlantAndEquipmentNet_12AC436CBECD7734DC933E943726363C_label_en-US" xlink:label="lab_us-gaap_PropertyPlantAndEquipmentNet_12AC436CBECD7734DC933E943726363C" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Property, Plant and Equipment, Net </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_PropertyPlantAndEquipmentNet" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentNet_12AC436CBECD7734DC933E943726363C" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentNet_12AC436CBECD7734DC933E943726363C" xlink:to="lab_us-gaap_PropertyPlantAndEquipmentNet_12AC436CBECD7734DC933E943726363C" xlink:type="arc"/>
<link:label id="lab_us-gaap_Goodwill_E0295EE9F404203141D93E943726BB90_terseLabel_en-US" xlink:label="lab_us-gaap_Goodwill_E0295EE9F404203141D93E943726BB90" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Goodwill </link:label>
<link:label id="lab_us-gaap_Goodwill_E0295EE9F404203141D93E943726BB90_label_en-US" xlink:label="lab_us-gaap_Goodwill_E0295EE9F404203141D93E943726BB90" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Goodwill </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_Goodwill" xlink:label="loc_us-gaap_Goodwill_E0295EE9F404203141D93E943726BB90" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_Goodwill_E0295EE9F404203141D93E943726BB90" xlink:to="lab_us-gaap_Goodwill_E0295EE9F404203141D93E943726BB90" xlink:type="arc"/>
<link:label id="lab_us-gaap_IntangibleAssetsNetExcludingGoodwill_78AE719B0122D89D0C9C3E943726DF8C_terseLabel_en-US" xlink:label="lab_us-gaap_IntangibleAssetsNetExcludingGoodwill_78AE719B0122D89D0C9C3E943726DF8C" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Intangible assets, net </link:label>
<link:label id="lab_us-gaap_IntangibleAssetsNetExcludingGoodwill_78AE719B0122D89D0C9C3E943726DF8C_label_en-US" xlink:label="lab_us-gaap_IntangibleAssetsNetExcludingGoodwill_78AE719B0122D89D0C9C3E943726DF8C" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Intangible Assets, Net (Excluding Goodwill) </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_IntangibleAssetsNetExcludingGoodwill" xlink:label="loc_us-gaap_IntangibleAssetsNetExcludingGoodwill_78AE719B0122D89D0C9C3E943726DF8C" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_IntangibleAssetsNetExcludingGoodwill_78AE719B0122D89D0C9C3E943726DF8C" xlink:to="lab_us-gaap_IntangibleAssetsNetExcludingGoodwill_78AE719B0122D89D0C9C3E943726DF8C" xlink:type="arc"/>
<link:label id="lab_us-gaap_OtherAssetsNoncurrent_60D5C9566EFC43314A033E94372618AB_terseLabel_en-US" xlink:label="lab_us-gaap_OtherAssetsNoncurrent_60D5C9566EFC43314A033E94372618AB" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Other assets </link:label>
<link:label id="lab_us-gaap_OtherAssetsNoncurrent_60D5C9566EFC43314A033E94372618AB_label_en-US" xlink:label="lab_us-gaap_OtherAssetsNoncurrent_60D5C9566EFC43314A033E94372618AB" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Other Assets, Noncurrent </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_OtherAssetsNoncurrent" xlink:label="loc_us-gaap_OtherAssetsNoncurrent_60D5C9566EFC43314A033E94372618AB" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_OtherAssetsNoncurrent_60D5C9566EFC43314A033E94372618AB" xlink:to="lab_us-gaap_OtherAssetsNoncurrent_60D5C9566EFC43314A033E94372618AB" xlink:type="arc"/>
<link:label id="lab_us-gaap_Assets_01DF720DEC1B5EDA3B063E9437268BD9_totalLabel_en-US" xlink:label="lab_us-gaap_Assets_01DF720DEC1B5EDA3B063E9437268BD9" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:type="resource" xml:lang="en-US"> Total Assets </link:label>
<link:label id="lab_us-gaap_Assets_01DF720DEC1B5EDA3B063E9437268BD9_label_en-US" xlink:label="lab_us-gaap_Assets_01DF720DEC1B5EDA3B063E9437268BD9" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Assets </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_Assets" xlink:label="loc_us-gaap_Assets_01DF720DEC1B5EDA3B063E9437268BD9" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_Assets_01DF720DEC1B5EDA3B063E9437268BD9" xlink:to="lab_us-gaap_Assets_01DF720DEC1B5EDA3B063E9437268BD9" xlink:type="arc"/>
<link:label id="lab_us-gaap_LiabilitiesAndStockholdersEquityAbstract_8BD7BBAC7064E2C848793E943726FCE8_terseLabel_en-US" xlink:label="lab_us-gaap_LiabilitiesAndStockholdersEquityAbstract_8BD7BBAC7064E2C848793E943726FCE8" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> LIABILITIES AND STOCKHOLDERS’ EQUITY (DEFICIT) </link:label>
<link:label id="lab_us-gaap_LiabilitiesAndStockholdersEquityAbstract_8BD7BBAC7064E2C848793E943726FCE8_label_en-US" xlink:label="lab_us-gaap_LiabilitiesAndStockholdersEquityAbstract_8BD7BBAC7064E2C848793E943726FCE8" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Liabilities and Equity [Abstract] </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_LiabilitiesAndStockholdersEquityAbstract" xlink:label="loc_us-gaap_LiabilitiesAndStockholdersEquityAbstract_8BD7BBAC7064E2C848793E943726FCE8" xlink:type="locator"/>
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<link:label id="lab_us-gaap_LiabilitiesCurrentAbstract_82657918665E36E15A483E94372698D1_terseLabel_en-US" xlink:label="lab_us-gaap_LiabilitiesCurrentAbstract_82657918665E36E15A483E94372698D1" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Current liabilities: </link:label>
<link:label id="lab_us-gaap_LiabilitiesCurrentAbstract_82657918665E36E15A483E94372698D1_label_en-US" xlink:label="lab_us-gaap_LiabilitiesCurrentAbstract_82657918665E36E15A483E94372698D1" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Liabilities, Current [Abstract] </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_LiabilitiesCurrentAbstract" xlink:label="loc_us-gaap_LiabilitiesCurrentAbstract_82657918665E36E15A483E94372698D1" xlink:type="locator"/>
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<link:label id="lab_us-gaap_AccountsPayableAndAccruedLiabilitiesCurrent_4CD3178F5364D2DDDDDD3E9437263309_terseLabel_en-US" xlink:label="lab_us-gaap_AccountsPayableAndAccruedLiabilitiesCurrent_4CD3178F5364D2DDDDDD3E9437263309" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Accounts payable and accrued liabilities </link:label>
<link:label id="lab_us-gaap_AccountsPayableAndAccruedLiabilitiesCurrent_4CD3178F5364D2DDDDDD3E9437263309_label_en-US" xlink:label="lab_us-gaap_AccountsPayableAndAccruedLiabilitiesCurrent_4CD3178F5364D2DDDDDD3E9437263309" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Accounts Payable and Accrued Liabilities, Current </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_AccountsPayableAndAccruedLiabilitiesCurrent" xlink:label="loc_us-gaap_AccountsPayableAndAccruedLiabilitiesCurrent_4CD3178F5364D2DDDDDD3E9437263309" xlink:type="locator"/>
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<link:label id="lab_us-gaap_DeferredRevenueCurrent_E702EBCC1748C0E401763E943726E19B_terseLabel_en-US" xlink:label="lab_us-gaap_DeferredRevenueCurrent_E702EBCC1748C0E401763E943726E19B" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Deferred revenues </link:label>
<link:label id="lab_us-gaap_DeferredRevenueCurrent_E702EBCC1748C0E401763E943726E19B_label_en-US" xlink:label="lab_us-gaap_DeferredRevenueCurrent_E702EBCC1748C0E401763E943726E19B" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Deferred Revenue, Current </link:label>
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<link:label id="lab_us-gaap_LongTermDebtCurrent_C296C699AA875736D1E73E9437269DE6_terseLabel_en-US" xlink:label="lab_us-gaap_LongTermDebtCurrent_C296C699AA875736D1E73E9437269DE6" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Current portion of long-term debt </link:label>
<link:label id="lab_us-gaap_LongTermDebtCurrent_C296C699AA875736D1E73E9437269DE6_label_en-US" xlink:label="lab_us-gaap_LongTermDebtCurrent_C296C699AA875736D1E73E9437269DE6" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Long-term Debt, Current Maturities </link:label>
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<link:label id="lab_us-gaap_LiabilitiesCurrent_795B50EAE1757A6D2B2F3E943726BA97_label_en-US" xlink:label="lab_us-gaap_LiabilitiesCurrent_795B50EAE1757A6D2B2F3E943726BA97" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Liabilities, Current </link:label>
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<link:label id="lab_us-gaap_OtherLiabilitiesNoncurrent_00DBFCBAA4DC2FE3498D3E943726D3E1_label_en-US" xlink:label="lab_us-gaap_OtherLiabilitiesNoncurrent_00DBFCBAA4DC2FE3498D3E943726D3E1" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Other Liabilities, Noncurrent </link:label>
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<link:label id="lab_us-gaap_Liabilities_DF0A918D637749D651743E9437278DFA_label_en-US" xlink:label="lab_us-gaap_Liabilities_DF0A918D637749D651743E9437278DFA" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Liabilities </link:label>
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<link:label id="lab_us-gaap_StockholdersEquityAbstract_7F2F098F87A3C7B104623E9437276418_terseLabel_en-US" xlink:label="lab_us-gaap_StockholdersEquityAbstract_7F2F098F87A3C7B104623E9437276418" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Stockholders’ Equity (Deficit): </link:label>
<link:label id="lab_us-gaap_StockholdersEquityAbstract_7F2F098F87A3C7B104623E9437276418_label_en-US" xlink:label="lab_us-gaap_StockholdersEquityAbstract_7F2F098F87A3C7B104623E9437276418" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Stockholders' Equity Attributable to Parent [Abstract] </link:label>
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<link:label id="lab_us-gaap_PreferredStockNumberOfSharesParValueAndOtherDisclosuresAbstract_9913E5B4AC0F347601C03E94372744DA_terseLabel_en-US" xlink:label="lab_us-gaap_PreferredStockNumberOfSharesParValueAndOtherDisclosuresAbstract_9913E5B4AC0F347601C03E94372744DA" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Preferred stock: </link:label>
<link:label id="lab_us-gaap_PreferredStockNumberOfSharesParValueAndOtherDisclosuresAbstract_9913E5B4AC0F347601C03E94372744DA_label_en-US" xlink:label="lab_us-gaap_PreferredStockNumberOfSharesParValueAndOtherDisclosuresAbstract_9913E5B4AC0F347601C03E94372744DA" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Preferred Stock, Number of Shares, Par Value and Other Disclosures [Abstract] </link:label>
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<link:label id="lab_us-gaap_PreferredStockValue_A70C44CAC6B93456353E3E9437274B37_terseLabel_en-US" xlink:label="lab_us-gaap_PreferredStockValue_A70C44CAC6B93456353E3E9437274B37" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> $.01 par value, authorized 5,000,000 shares; none issued or outstanding </link:label>
<link:label id="lab_us-gaap_PreferredStockValue_A70C44CAC6B93456353E3E9437274B37_label_en-US" xlink:label="lab_us-gaap_PreferredStockValue_A70C44CAC6B93456353E3E9437274B37" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Preferred Stock, Value, Issued </link:label>
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<link:label id="lab_us-gaap_CommonStockNumberOfSharesParValueAndOtherDisclosuresAbstract_011418C0FC05CE774B593E943727376E_terseLabel_en-US" xlink:label="lab_us-gaap_CommonStockNumberOfSharesParValueAndOtherDisclosuresAbstract_011418C0FC05CE774B593E943727376E" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Common stock: </link:label>
<link:label id="lab_us-gaap_CommonStockNumberOfSharesParValueAndOtherDisclosuresAbstract_011418C0FC05CE774B593E943727376E_label_en-US" xlink:label="lab_us-gaap_CommonStockNumberOfSharesParValueAndOtherDisclosuresAbstract_011418C0FC05CE774B593E943727376E" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Common Stock, Number of Shares, Par Value and Other Disclosures [Abstract] </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_CommonStockNumberOfSharesParValueAndOtherDisclosuresAbstract" xlink:label="loc_us-gaap_CommonStockNumberOfSharesParValueAndOtherDisclosuresAbstract_011418C0FC05CE774B593E943727376E" xlink:type="locator"/>
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<link:label id="lab_us-gaap_CommonStockValue_39625301D055C9A99D4D3E943727B0B8_terseLabel_en-US" xlink:label="lab_us-gaap_CommonStockValue_39625301D055C9A99D4D3E943727B0B8" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> $.0005 par value, authorized 250,000,000 shares for both periods; 156,234,415 shares issued for both periods </link:label>
<link:label id="lab_us-gaap_CommonStockValue_39625301D055C9A99D4D3E943727B0B8_label_en-US" xlink:label="lab_us-gaap_CommonStockValue_39625301D055C9A99D4D3E943727B0B8" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Common Stock, Value, Issued </link:label>
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<link:label id="lab_us-gaap_AdditionalPaidInCapital_973329B90A3B5D1E8F9D3E9437272227_terseLabel_en-US" xlink:label="lab_us-gaap_AdditionalPaidInCapital_973329B90A3B5D1E8F9D3E9437272227" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Additional paid-in capital </link:label>
<link:label id="lab_us-gaap_AdditionalPaidInCapital_973329B90A3B5D1E8F9D3E9437272227_label_en-US" xlink:label="lab_us-gaap_AdditionalPaidInCapital_973329B90A3B5D1E8F9D3E9437272227" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Additional Paid in Capital </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_AdditionalPaidInCapital" xlink:label="loc_us-gaap_AdditionalPaidInCapital_973329B90A3B5D1E8F9D3E9437272227" xlink:type="locator"/>
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<link:label id="lab_us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax_585D621A4F666DA7695A3E9437271370_terseLabel_en-US" xlink:label="lab_us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax_585D621A4F666DA7695A3E9437271370" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Accumulated other comprehensive loss, net </link:label>
<link:label id="lab_us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax_585D621A4F666DA7695A3E9437271370_label_en-US" xlink:label="lab_us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax_585D621A4F666DA7695A3E9437271370" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Accumulated Other Comprehensive Income (Loss), Net of Tax </link:label>
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<link:label id="lab_us-gaap_RetainedEarningsAccumulatedDeficit_CFE1502E32E37D94065A3E9437271F22_label_en-US" xlink:label="lab_us-gaap_RetainedEarningsAccumulatedDeficit_CFE1502E32E37D94065A3E9437271F22" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Retained Earnings (Accumulated Deficit) </link:label>
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<link:label id="lab_us-gaap_TreasuryStockValue_6F179D1AACB5278CFDBA3E943727A461_negatedLabel_en-US" xlink:label="lab_us-gaap_TreasuryStockValue_6F179D1AACB5278CFDBA3E943727A461" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:type="resource" xml:lang="en-US"> Treasury stock, at cost, 73,583,172 and 73,896,245 common shares, respectively </link:label>
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<link:label id="lab_us-gaap_MediaContentMember_B7AF02728A61643FA7C83E9436E18BC9_terseLabel_en-US" xlink:label="lab_us-gaap_MediaContentMember_B7AF02728A61643FA7C83E9436E18BC9" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Content </link:label>
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<link:label id="lab_us-gaap_ComputerSoftwareIntangibleAssetMember_2D82CDEA7339B5DAB5733E9436E17BFF_terseLabel_en-US" xlink:label="lab_us-gaap_ComputerSoftwareIntangibleAssetMember_2D82CDEA7339B5DAB5733E9436E17BFF" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Software </link:label>
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<link:label id="lab_us-gaap_NoncompeteAgreementsMember_B2E012176D7CC8FC199F3E9436E182CD_terseLabel_en-US" xlink:label="lab_us-gaap_NoncompeteAgreementsMember_B2E012176D7CC8FC199F3E9436E182CD" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Non-Compete </link:label>
<link:label id="lab_us-gaap_NoncompeteAgreementsMember_B2E012176D7CC8FC199F3E9436E182CD_label_en-US" xlink:label="lab_us-gaap_NoncompeteAgreementsMember_B2E012176D7CC8FC199F3E9436E182CD" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Noncompete Agreements [Member] </link:label>
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<link:label id="lab_us-gaap_FiniteLivedIntangibleAssetsForeignCurrencyTranslationGainLoss_463B8D6B7963AACCD7DC3E9436E2B106_label_en-US" xlink:label="lab_us-gaap_FiniteLivedIntangibleAssetsForeignCurrencyTranslationGainLoss_463B8D6B7963AACCD7DC3E9436E2B106" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Finite Lived Intangible Assets, Foreign Currency Translation Gain (Loss) </link:label>
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<link:label id="lab_us-gaap_FiniteLivedIntangibleAssetsGross_1C5BD62178D6B2C499F13E9436E22FC7_periodEndLabel_en-US" xlink:label="lab_us-gaap_FiniteLivedIntangibleAssetsGross_1C5BD62178D6B2C499F13E9436E22FC7" xlink:role="http://www.xbrl.org/2003/role/periodEndLabel" xlink:type="resource" xml:lang="en-US"> Gross cost </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsGross" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsGross_1C5BD62178D6B2C499F13E9436E22FC7" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsGross_1C5BD62178D6B2C499F13E9436E22FC7" xlink:to="lab_us-gaap_FiniteLivedIntangibleAssetsGross_1C5BD62178D6B2C499F13E9436E22FC7" xlink:type="arc"/>
<link:label id="lab_us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization_4A54249514CB63AF29DC3E9436E248BF_negatedTerseLabel_en-US" xlink:label="lab_us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization_4A54249514CB63AF29DC3E9436E248BF" xlink:role="http://www.xbrl.org/2009/role/negatedTerseLabel" xlink:type="resource" xml:lang="en-US"> Accumulated amortization </link:label>
<link:label id="lab_us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization_4A54249514CB63AF29DC3E9436E248BF_label_en-US" xlink:label="lab_us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization_4A54249514CB63AF29DC3E9436E248BF" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Finite-Lived Intangible Assets, Accumulated Amortization </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization_4A54249514CB63AF29DC3E9436E248BF" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization_4A54249514CB63AF29DC3E9436E248BF" xlink:to="lab_us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization_4A54249514CB63AF29DC3E9436E248BF" xlink:type="arc"/>
<link:label id="lab_us-gaap_FiniteLivedIntangibleAssetsNet_63C520DADC22F787F1193E9436E21F00_totalLabel_en-US" xlink:label="lab_us-gaap_FiniteLivedIntangibleAssetsNet_63C520DADC22F787F1193E9436E21F00" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:type="resource" xml:lang="en-US"> Finite-lived intangible assets, net </link:label>
<link:label id="lab_us-gaap_FiniteLivedIntangibleAssetsNet_63C520DADC22F787F1193E9436E21F00_label_en-US" xlink:label="lab_us-gaap_FiniteLivedIntangibleAssetsNet_63C520DADC22F787F1193E9436E21F00" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Finite-Lived Intangible Assets, Net </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsNet" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsNet_63C520DADC22F787F1193E9436E21F00" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsNet_63C520DADC22F787F1193E9436E21F00" xlink:to="lab_us-gaap_FiniteLivedIntangibleAssetsNet_63C520DADC22F787F1193E9436E21F00" xlink:type="arc"/>
<link:label id="lab_us-gaap_EquityAbstract_CD594186157BA357701E3ED1D5BE6281_label_en-US" xlink:label="lab_us-gaap_EquityAbstract_CD594186157BA357701E3ED1D5BE6281" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Equity [Abstract] </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_EquityAbstract" xlink:label="loc_us-gaap_EquityAbstract_CD594186157BA357701E3ED1D5BE6281" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_EquityAbstract_CD594186157BA357701E3ED1D5BE6281" xlink:to="lab_us-gaap_EquityAbstract_CD594186157BA357701E3ED1D5BE6281" xlink:type="arc"/>
<link:label id="lab_us-gaap_CommonStockMember_A834E4DC68EE3E2CE6353ED1D5BE00CB_terseLabel_en-US" xlink:label="lab_us-gaap_CommonStockMember_A834E4DC68EE3E2CE6353ED1D5BE00CB" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Common Stock </link:label>
<link:label id="lab_us-gaap_CommonStockMember_A834E4DC68EE3E2CE6353ED1D5BE00CB_label_en-US" xlink:label="lab_us-gaap_CommonStockMember_A834E4DC68EE3E2CE6353ED1D5BE00CB" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Common Stock [Member] </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_CommonStockMember" xlink:label="loc_us-gaap_CommonStockMember_A834E4DC68EE3E2CE6353ED1D5BE00CB" xlink:type="locator"/>
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<link:label id="lab_us-gaap_TreasuryStockMember_71C51E10969DFA03AE4B3ED1D5BE56CD_terseLabel_en-US" xlink:label="lab_us-gaap_TreasuryStockMember_71C51E10969DFA03AE4B3ED1D5BE56CD" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Treasury Stock </link:label>
<link:label id="lab_us-gaap_TreasuryStockMember_71C51E10969DFA03AE4B3ED1D5BE56CD_label_en-US" xlink:label="lab_us-gaap_TreasuryStockMember_71C51E10969DFA03AE4B3ED1D5BE56CD" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Treasury Stock [Member] </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_TreasuryStockMember" xlink:label="loc_us-gaap_TreasuryStockMember_71C51E10969DFA03AE4B3ED1D5BE56CD" xlink:type="locator"/>
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<link:label id="lab_it_CommonStockOutstandingRollForwardRollForward_F98CF10A9AA3471BE3333ED1D5BE4652_terseLabel_en-US" xlink:label="lab_it_CommonStockOutstandingRollForwardRollForward_F98CF10A9AA3471BE3333ED1D5BE4652" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Common Stock Outstanding Roll Forward [Roll Forward] </link:label>
<link:label id="lab_it_CommonStockOutstandingRollForwardRollForward_F98CF10A9AA3471BE3333ED1D5BE4652_label_en-US" xlink:label="lab_it_CommonStockOutstandingRollForwardRollForward_F98CF10A9AA3471BE3333ED1D5BE4652" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Common Stock Outstanding Roll Forward [Roll Forward] </link:label>
<link:label id="lab_it_CommonStockOutstandingRollForwardRollForward_F98CF10A9AA3471BE3333ED1D5BE4652_documentation_en-US" xlink:label="lab_it_CommonStockOutstandingRollForwardRollForward_F98CF10A9AA3471BE3333ED1D5BE4652" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US"> Common Stock Outstanding Roll Forward [Roll Forward] </link:label>
<link:loc xlink:href="it-20161231.xsd#it_CommonStockOutstandingRollForwardRollForward" xlink:label="loc_it_CommonStockOutstandingRollForwardRollForward_F98CF10A9AA3471BE3333ED1D5BE4652" xlink:type="locator"/>
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<link:label id="lab_us-gaap_SharesOutstanding_C860EBD72775457016383ED1D5BE1D05_periodStartLabel_en-US" xlink:label="lab_us-gaap_SharesOutstanding_C860EBD72775457016383ED1D5BE1D05" xlink:role="http://www.xbrl.org/2003/role/periodStartLabel" xlink:type="resource" xml:lang="en-US"> Beginning Balance </link:label>
<link:label id="lab_us-gaap_SharesOutstanding_C860EBD72775457016383ED1D5BE1D05_label_en-US" xlink:label="lab_us-gaap_SharesOutstanding_C860EBD72775457016383ED1D5BE1D05" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Shares, Outstanding </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_SharesOutstanding" xlink:label="loc_us-gaap_SharesOutstanding_C860EBD72775457016383ED1D5BE1D05" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_SharesOutstanding_C860EBD72775457016383ED1D5BE1D05" xlink:to="lab_us-gaap_SharesOutstanding_C860EBD72775457016383ED1D5BE1D05" xlink:type="arc"/>
<link:label id="lab_us-gaap_StockIssuedDuringPeriodSharesEmployeeStockPurchasePlans_0F5139303DF51CE5B1343ED1D5BE6178_terseLabel_en-US" xlink:label="lab_us-gaap_StockIssuedDuringPeriodSharesEmployeeStockPurchasePlans_0F5139303DF51CE5B1343ED1D5BE6178" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Issuances under stock plans </link:label>
<link:label id="lab_us-gaap_StockIssuedDuringPeriodSharesEmployeeStockPurchasePlans_0F5139303DF51CE5B1343ED1D5BE6178_label_en-US" xlink:label="lab_us-gaap_StockIssuedDuringPeriodSharesEmployeeStockPurchasePlans_0F5139303DF51CE5B1343ED1D5BE6178" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Stock Issued During Period, Shares, Employee Stock Purchase Plans </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_StockIssuedDuringPeriodSharesEmployeeStockPurchasePlans" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesEmployeeStockPurchasePlans_0F5139303DF51CE5B1343ED1D5BE6178" xlink:type="locator"/>
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<link:label id="lab_us-gaap_TreasuryStockSharesAcquired_A5B826FF29D4BD3D8A563ED1D5BEB606_verboseLabel_en-US" xlink:label="lab_us-gaap_TreasuryStockSharesAcquired_A5B826FF29D4BD3D8A563ED1D5BEB606" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:type="resource" xml:lang="en-US"> Purchases for treasury </link:label>
<link:label id="lab_us-gaap_TreasuryStockSharesAcquired_A5B826FF29D4BD3D8A563ED1D5BEB606_label_en-US" xlink:label="lab_us-gaap_TreasuryStockSharesAcquired_A5B826FF29D4BD3D8A563ED1D5BEB606" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Treasury Stock, Shares, Acquired </link:label>
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<link:label id="lab_us-gaap_SharesOutstanding_C0FB21BD43F9BD2235793ED1D5BE355B_periodEndLabel_en-US" xlink:label="lab_us-gaap_SharesOutstanding_C0FB21BD43F9BD2235793ED1D5BE355B" xlink:role="http://www.xbrl.org/2003/role/periodEndLabel" xlink:type="resource" xml:lang="en-US"> Ending Balance </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_SharesOutstanding" xlink:label="loc_us-gaap_SharesOutstanding_C0FB21BD43F9BD2235793ED1D5BE355B" xlink:type="locator"/>
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<link:label id="lab_us-gaap_SubsequentEventsAbstract_01991978BF24914079AD47C09BDBC9AC_label_en-US" xlink:label="lab_us-gaap_SubsequentEventsAbstract_01991978BF24914079AD47C09BDBC9AC" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Subsequent Events [Abstract] </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_SubsequentEventsAbstract" xlink:label="loc_us-gaap_SubsequentEventsAbstract_01991978BF24914079AD47C09BDBC9AC" xlink:type="locator"/>
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<link:label id="lab_us-gaap_CreditFacilityAxis_A3B082371C3630B275BB47C09BDDE19A_terseLabel_en-US" xlink:label="lab_us-gaap_CreditFacilityAxis_A3B082371C3630B275BB47C09BDDE19A" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Credit Facility [Axis] </link:label>
<link:label id="lab_us-gaap_CreditFacilityAxis_A3B082371C3630B275BB47C09BDDE19A_label_en-US" xlink:label="lab_us-gaap_CreditFacilityAxis_A3B082371C3630B275BB47C09BDDE19A" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Credit Facility [Axis] </link:label>
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<link:label id="lab_us-gaap_CreditFacilityDomain_DAEC577D467729DF53AE47C09BDD4C88_terseLabel_en-US" xlink:label="lab_us-gaap_CreditFacilityDomain_DAEC577D467729DF53AE47C09BDD4C88" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Credit Facility [Domain] </link:label>
<link:label id="lab_us-gaap_CreditFacilityDomain_DAEC577D467729DF53AE47C09BDD4C88_label_en-US" xlink:label="lab_us-gaap_CreditFacilityDomain_DAEC577D467729DF53AE47C09BDD4C88" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Credit Facility [Domain] </link:label>
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<link:label id="lab_us-gaap_SecuredDebtMember_C958B95761F96012347A47C09BDDFBDB_terseLabel_en-US" xlink:label="lab_us-gaap_SecuredDebtMember_C958B95761F96012347A47C09BDDFBDB" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Secured Debt </link:label>
<link:label id="lab_us-gaap_SecuredDebtMember_C958B95761F96012347A47C09BDDFBDB_label_en-US" xlink:label="lab_us-gaap_SecuredDebtMember_C958B95761F96012347A47C09BDDFBDB" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Secured Debt [Member] </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_SecuredDebtMember" xlink:label="loc_us-gaap_SecuredDebtMember_C958B95761F96012347A47C09BDDFBDB" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_SecuredDebtMember_C958B95761F96012347A47C09BDDFBDB" xlink:to="lab_us-gaap_SecuredDebtMember_C958B95761F96012347A47C09BDDFBDB" xlink:type="arc"/>
<link:label id="lab_us-gaap_UnsecuredDebtMember_C9D5E7F45ED9C5C3FB7647C3894DC303_terseLabel_en-US" xlink:label="lab_us-gaap_UnsecuredDebtMember_C9D5E7F45ED9C5C3FB7647C3894DC303" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Unsecured Debt </link:label>
<link:label id="lab_us-gaap_UnsecuredDebtMember_C9D5E7F45ED9C5C3FB7647C3894DC303_label_en-US" xlink:label="lab_us-gaap_UnsecuredDebtMember_C9D5E7F45ED9C5C3FB7647C3894DC303" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Unsecured Debt [Member] </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_UnsecuredDebtMember" xlink:label="loc_us-gaap_UnsecuredDebtMember_C9D5E7F45ED9C5C3FB7647C3894DC303" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_UnsecuredDebtMember_C9D5E7F45ED9C5C3FB7647C3894DC303" xlink:to="lab_us-gaap_UnsecuredDebtMember_C9D5E7F45ED9C5C3FB7647C3894DC303" xlink:type="arc"/>
<link:label id="lab_us-gaap_BusinessAcquisitionAxis_D9A02715A621DA2E566347C09BDE0F6A_terseLabel_en-US" xlink:label="lab_us-gaap_BusinessAcquisitionAxis_D9A02715A621DA2E566347C09BDE0F6A" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Business Acquisition [Axis] </link:label>
<link:label id="lab_us-gaap_BusinessAcquisitionAxis_D9A02715A621DA2E566347C09BDE0F6A_label_en-US" xlink:label="lab_us-gaap_BusinessAcquisitionAxis_D9A02715A621DA2E566347C09BDE0F6A" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Business Acquisition [Axis] </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_BusinessAcquisitionAxis" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_D9A02715A621DA2E566347C09BDE0F6A" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_D9A02715A621DA2E566347C09BDE0F6A" xlink:to="lab_us-gaap_BusinessAcquisitionAxis_D9A02715A621DA2E566347C09BDE0F6A" xlink:type="arc"/>
<link:label id="lab_us-gaap_BusinessAcquisitionAcquireeDomain_BB945675F7B7C26A8ED747C09BDE8B08_terseLabel_en-US" xlink:label="lab_us-gaap_BusinessAcquisitionAcquireeDomain_BB945675F7B7C26A8ED747C09BDE8B08" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Business Acquisition, Acquiree [Domain] </link:label>
<link:label id="lab_us-gaap_BusinessAcquisitionAcquireeDomain_BB945675F7B7C26A8ED747C09BDE8B08_label_en-US" xlink:label="lab_us-gaap_BusinessAcquisitionAcquireeDomain_BB945675F7B7C26A8ED747C09BDE8B08" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Business Acquisition, Acquiree [Domain] </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_BB945675F7B7C26A8ED747C09BDE8B08" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_BB945675F7B7C26A8ED747C09BDE8B08" xlink:to="lab_us-gaap_BusinessAcquisitionAcquireeDomain_BB945675F7B7C26A8ED747C09BDE8B08" xlink:type="arc"/>
<link:label id="lab_it_CEBInc.Member_D9871B3BF8950830594A47C09BDEA7DE_terseLabel_en-US" xlink:label="lab_it_CEBInc.Member_D9871B3BF8950830594A47C09BDEA7DE" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> CEB </link:label>
<link:label id="lab_it_CEBInc.Member_D9871B3BF8950830594A47C09BDEA7DE_label_en-US" xlink:label="lab_it_CEBInc.Member_D9871B3BF8950830594A47C09BDEA7DE" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> CEB, Inc. [Member] </link:label>
<link:label id="lab_it_CEBInc.Member_D9871B3BF8950830594A47C09BDEA7DE_documentation_en-US" xlink:label="lab_it_CEBInc.Member_D9871B3BF8950830594A47C09BDEA7DE" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US"> CEB, Inc. </link:label>
<link:loc xlink:href="it-20161231.xsd#it_CEBInc.Member" xlink:label="loc_it_CEBInc.Member_D9871B3BF8950830594A47C09BDEA7DE" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_it_CEBInc.Member_D9871B3BF8950830594A47C09BDEA7DE" xlink:to="lab_it_CEBInc.Member_D9871B3BF8950830594A47C09BDEA7DE" xlink:type="arc"/>
<link:label id="lab_us-gaap_ShortTermDebtTypeAxis_E934789A79A45BEB40DE47C09BDE5458_terseLabel_en-US" xlink:label="lab_us-gaap_ShortTermDebtTypeAxis_E934789A79A45BEB40DE47C09BDE5458" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Short-term Debt, Type [Axis] </link:label>
<link:label id="lab_us-gaap_ShortTermDebtTypeAxis_E934789A79A45BEB40DE47C09BDE5458_label_en-US" xlink:label="lab_us-gaap_ShortTermDebtTypeAxis_E934789A79A45BEB40DE47C09BDE5458" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Short-term Debt, Type [Axis] </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ShortTermDebtTypeAxis" xlink:label="loc_us-gaap_ShortTermDebtTypeAxis_E934789A79A45BEB40DE47C09BDE5458" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ShortTermDebtTypeAxis_E934789A79A45BEB40DE47C09BDE5458" xlink:to="lab_us-gaap_ShortTermDebtTypeAxis_E934789A79A45BEB40DE47C09BDE5458" xlink:type="arc"/>
<link:label id="lab_us-gaap_ShortTermDebtTypeDomain_71818C8657BBE883425447C09BDEC300_terseLabel_en-US" xlink:label="lab_us-gaap_ShortTermDebtTypeDomain_71818C8657BBE883425447C09BDEC300" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Short-term Debt, Type [Domain] </link:label>
<link:label id="lab_us-gaap_ShortTermDebtTypeDomain_71818C8657BBE883425447C09BDEC300_label_en-US" xlink:label="lab_us-gaap_ShortTermDebtTypeDomain_71818C8657BBE883425447C09BDEC300" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Short-term Debt, Type [Domain] </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ShortTermDebtTypeDomain" xlink:label="loc_us-gaap_ShortTermDebtTypeDomain_71818C8657BBE883425447C09BDEC300" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ShortTermDebtTypeDomain_71818C8657BBE883425447C09BDEC300" xlink:to="lab_us-gaap_ShortTermDebtTypeDomain_71818C8657BBE883425447C09BDEC300" xlink:type="arc"/>
<link:label id="lab_us-gaap_BridgeLoanMember_B59628BA603CA4BD6A1647C09BDE3555_terseLabel_en-US" xlink:label="lab_us-gaap_BridgeLoanMember_B59628BA603CA4BD6A1647C09BDE3555" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Bridge Loan </link:label>
<link:label id="lab_us-gaap_BridgeLoanMember_B59628BA603CA4BD6A1647C09BDE3555_label_en-US" xlink:label="lab_us-gaap_BridgeLoanMember_B59628BA603CA4BD6A1647C09BDE3555" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Bridge Loan [Member] </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_BridgeLoanMember" xlink:label="loc_us-gaap_BridgeLoanMember_B59628BA603CA4BD6A1647C09BDE3555" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_BridgeLoanMember_B59628BA603CA4BD6A1647C09BDE3555" xlink:to="lab_us-gaap_BridgeLoanMember_B59628BA603CA4BD6A1647C09BDE3555" xlink:type="arc"/>
<link:label id="lab_us-gaap_SubsequentEventTypeAxis_4433404CFC5093AC541747C09BDE70E7_terseLabel_en-US" xlink:label="lab_us-gaap_SubsequentEventTypeAxis_4433404CFC5093AC541747C09BDE70E7" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Subsequent Event Type [Axis] </link:label>
<link:label id="lab_us-gaap_SubsequentEventTypeAxis_4433404CFC5093AC541747C09BDE70E7_label_en-US" xlink:label="lab_us-gaap_SubsequentEventTypeAxis_4433404CFC5093AC541747C09BDE70E7" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Subsequent Event Type [Axis] </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_SubsequentEventTypeAxis" xlink:label="loc_us-gaap_SubsequentEventTypeAxis_4433404CFC5093AC541747C09BDE70E7" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_4433404CFC5093AC541747C09BDE70E7" xlink:to="lab_us-gaap_SubsequentEventTypeAxis_4433404CFC5093AC541747C09BDE70E7" xlink:type="arc"/>
<link:label id="lab_us-gaap_SubsequentEventTypeDomain_F538435A067ABB579C8C47C09BDEF5F9_terseLabel_en-US" xlink:label="lab_us-gaap_SubsequentEventTypeDomain_F538435A067ABB579C8C47C09BDEF5F9" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Subsequent Event Type [Domain] </link:label>
<link:label id="lab_us-gaap_SubsequentEventTypeDomain_F538435A067ABB579C8C47C09BDEF5F9_label_en-US" xlink:label="lab_us-gaap_SubsequentEventTypeDomain_F538435A067ABB579C8C47C09BDEF5F9" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Subsequent Event Type [Domain] </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_SubsequentEventTypeDomain" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_F538435A067ABB579C8C47C09BDEF5F9" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_SubsequentEventTypeDomain_F538435A067ABB579C8C47C09BDEF5F9" xlink:to="lab_us-gaap_SubsequentEventTypeDomain_F538435A067ABB579C8C47C09BDEF5F9" xlink:type="arc"/>
<link:label id="lab_us-gaap_SubsequentEventMember_99E7C7BC2FFCFAAB0A2C47C09BDEC3A0_terseLabel_en-US" xlink:label="lab_us-gaap_SubsequentEventMember_99E7C7BC2FFCFAAB0A2C47C09BDEC3A0" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Subsequent Event </link:label>
<link:label id="lab_us-gaap_SubsequentEventMember_99E7C7BC2FFCFAAB0A2C47C09BDEC3A0_label_en-US" xlink:label="lab_us-gaap_SubsequentEventMember_99E7C7BC2FFCFAAB0A2C47C09BDEC3A0" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Subsequent Event [Member] </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_SubsequentEventMember" xlink:label="loc_us-gaap_SubsequentEventMember_99E7C7BC2FFCFAAB0A2C47C09BDEC3A0" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_SubsequentEventMember_99E7C7BC2FFCFAAB0A2C47C09BDEC3A0" xlink:to="lab_us-gaap_SubsequentEventMember_99E7C7BC2FFCFAAB0A2C47C09BDEC3A0" xlink:type="arc"/>
<link:label id="lab_us-gaap_SubsequentEventLineItems_A5C99203893E2942839F47C09BDEE7BD_terseLabel_en-US" xlink:label="lab_us-gaap_SubsequentEventLineItems_A5C99203893E2942839F47C09BDEE7BD" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Subsequent Event [Line Items] </link:label>
<link:label id="lab_us-gaap_SubsequentEventLineItems_A5C99203893E2942839F47C09BDEE7BD_label_en-US" xlink:label="lab_us-gaap_SubsequentEventLineItems_A5C99203893E2942839F47C09BDEE7BD" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Subsequent Event [Line Items] </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_SubsequentEventLineItems" xlink:label="loc_us-gaap_SubsequentEventLineItems_A5C99203893E2942839F47C09BDEE7BD" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_SubsequentEventLineItems_A5C99203893E2942839F47C09BDEE7BD" xlink:to="lab_us-gaap_SubsequentEventLineItems_A5C99203893E2942839F47C09BDEE7BD" xlink:type="arc"/>
<link:label id="lab_it_AnticipatedPaymentstoAcquireBusinessGross_F41F4D0C12C13CC44DE347C09BDE3037_terseLabel_en-US" xlink:label="lab_it_AnticipatedPaymentstoAcquireBusinessGross_F41F4D0C12C13CC44DE347C09BDE3037" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Anticipated aggregate purchase price </link:label>
<link:label id="lab_it_AnticipatedPaymentstoAcquireBusinessGross_F41F4D0C12C13CC44DE347C09BDE3037_label_en-US" xlink:label="lab_it_AnticipatedPaymentstoAcquireBusinessGross_F41F4D0C12C13CC44DE347C09BDE3037" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Anticipated Payments to Acquire Business, Gross </link:label>
<link:label id="lab_it_AnticipatedPaymentstoAcquireBusinessGross_F41F4D0C12C13CC44DE347C09BDE3037_documentation_en-US" xlink:label="lab_it_AnticipatedPaymentstoAcquireBusinessGross_F41F4D0C12C13CC44DE347C09BDE3037" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US"> Anticipated Payments to Acquire Business, Gross </link:label>
<link:loc xlink:href="it-20161231.xsd#it_AnticipatedPaymentstoAcquireBusinessGross" xlink:label="loc_it_AnticipatedPaymentstoAcquireBusinessGross_F41F4D0C12C13CC44DE347C09BDE3037" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_it_AnticipatedPaymentstoAcquireBusinessGross_F41F4D0C12C13CC44DE347C09BDE3037" xlink:to="lab_it_AnticipatedPaymentstoAcquireBusinessGross_F41F4D0C12C13CC44DE347C09BDE3037" xlink:type="arc"/>
<link:label id="lab_it_BusinessCombinationConsiderationLiabilitiesAnticipatedtobeIncurred_6DAAAF58599E8A60CDC147C09BDE3E9C_terseLabel_en-US" xlink:label="lab_it_BusinessCombinationConsiderationLiabilitiesAnticipatedtobeIncurred_6DAAAF58599E8A60CDC147C09BDE3E9C" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Business combination, liabilities anticipated to be incurred </link:label>
<link:label id="lab_it_BusinessCombinationConsiderationLiabilitiesAnticipatedtobeIncurred_6DAAAF58599E8A60CDC147C09BDE3E9C_label_en-US" xlink:label="lab_it_BusinessCombinationConsiderationLiabilitiesAnticipatedtobeIncurred_6DAAAF58599E8A60CDC147C09BDE3E9C" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Business Combination, Consideration, Liabilities Anticipated to be Incurred </link:label>
<link:label id="lab_it_BusinessCombinationConsiderationLiabilitiesAnticipatedtobeIncurred_6DAAAF58599E8A60CDC147C09BDE3E9C_documentation_en-US" xlink:label="lab_it_BusinessCombinationConsiderationLiabilitiesAnticipatedtobeIncurred_6DAAAF58599E8A60CDC147C09BDE3E9C" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US"> Business Combination, Consideration, Liabilities Anticipated to be Incurred </link:label>
<link:loc xlink:href="it-20161231.xsd#it_BusinessCombinationConsiderationLiabilitiesAnticipatedtobeIncurred" xlink:label="loc_it_BusinessCombinationConsiderationLiabilitiesAnticipatedtobeIncurred_6DAAAF58599E8A60CDC147C09BDE3E9C" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_it_BusinessCombinationConsiderationLiabilitiesAnticipatedtobeIncurred_6DAAAF58599E8A60CDC147C09BDE3E9C" xlink:to="lab_it_BusinessCombinationConsiderationLiabilitiesAnticipatedtobeIncurred_6DAAAF58599E8A60CDC147C09BDE3E9C" xlink:type="arc"/>
<link:label id="lab_us-gaap_DebtInstrumentTerm_D215BE6BF1FD9989103747C09BDECA4D_terseLabel_en-US" xlink:label="lab_us-gaap_DebtInstrumentTerm_D215BE6BF1FD9989103747C09BDECA4D" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Debt instrument term </link:label>
<link:label id="lab_us-gaap_DebtInstrumentTerm_D215BE6BF1FD9989103747C09BDECA4D_label_en-US" xlink:label="lab_us-gaap_DebtInstrumentTerm_D215BE6BF1FD9989103747C09BDECA4D" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Debt Instrument, Term </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_DebtInstrumentTerm" xlink:label="loc_us-gaap_DebtInstrumentTerm_D215BE6BF1FD9989103747C09BDECA4D" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DebtInstrumentTerm_D215BE6BF1FD9989103747C09BDECA4D" xlink:to="lab_us-gaap_DebtInstrumentTerm_D215BE6BF1FD9989103747C09BDECA4D" xlink:type="arc"/>
<link:label id="lab_us-gaap_LineOfCreditFacilityCapacityAvailableForSpecificPurposeOtherThanForTradePurchases_10AEEC36A2876ADB4B5B47C09BDE291B_terseLabel_en-US" xlink:label="lab_us-gaap_LineOfCreditFacilityCapacityAvailableForSpecificPurposeOtherThanForTradePurchases_10AEEC36A2876ADB4B5B47C09BDE291B" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Line of credit, capacity available for specific purpose </link:label>
<link:label id="lab_us-gaap_LineOfCreditFacilityCapacityAvailableForSpecificPurposeOtherThanForTradePurchases_10AEEC36A2876ADB4B5B47C09BDE291B_label_en-US" xlink:label="lab_us-gaap_LineOfCreditFacilityCapacityAvailableForSpecificPurposeOtherThanForTradePurchases_10AEEC36A2876ADB4B5B47C09BDE291B" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Line of Credit Facility, Capacity Available for Specific Purpose Other than for Trade Purchases </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_LineOfCreditFacilityCapacityAvailableForSpecificPurposeOtherThanForTradePurchases" xlink:label="loc_us-gaap_LineOfCreditFacilityCapacityAvailableForSpecificPurposeOtherThanForTradePurchases_10AEEC36A2876ADB4B5B47C09BDE291B" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_LineOfCreditFacilityCapacityAvailableForSpecificPurposeOtherThanForTradePurchases_10AEEC36A2876ADB4B5B47C09BDE291B" xlink:to="lab_us-gaap_LineOfCreditFacilityCapacityAvailableForSpecificPurposeOtherThanForTradePurchases_10AEEC36A2876ADB4B5B47C09BDE291B" xlink:type="arc"/>
<link:label id="lab_us-gaap_ScheduleOfRevenuesFromExternalCustomersAndLongLivedAssetsTable_305ED5354ED96A0DF20AB4CBF1EF0B5F_terseLabel_en-US" xlink:label="lab_us-gaap_ScheduleOfRevenuesFromExternalCustomersAndLongLivedAssetsTable_305ED5354ED96A0DF20AB4CBF1EF0B5F" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Schedule of Revenues from External Customers and Long-Lived Assets [Table] </link:label>
<link:label id="lab_us-gaap_ScheduleOfRevenuesFromExternalCustomersAndLongLivedAssetsTable_305ED5354ED96A0DF20AB4CBF1EF0B5F_label_en-US" xlink:label="lab_us-gaap_ScheduleOfRevenuesFromExternalCustomersAndLongLivedAssetsTable_305ED5354ED96A0DF20AB4CBF1EF0B5F" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Schedule of Revenues from External Customers and Long-Lived Assets [Table] </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ScheduleOfRevenuesFromExternalCustomersAndLongLivedAssetsTable" xlink:label="loc_us-gaap_ScheduleOfRevenuesFromExternalCustomersAndLongLivedAssetsTable_305ED5354ED96A0DF20AB4CBF1EF0B5F" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ScheduleOfRevenuesFromExternalCustomersAndLongLivedAssetsTable_305ED5354ED96A0DF20AB4CBF1EF0B5F" xlink:to="lab_us-gaap_ScheduleOfRevenuesFromExternalCustomersAndLongLivedAssetsTable_305ED5354ED96A0DF20AB4CBF1EF0B5F" xlink:type="arc"/>
<link:label id="lab_us-gaap_StatementGeographicalAxis_04511CB093243C09889AB4CBF1F0B566_terseLabel_en-US" xlink:label="lab_us-gaap_StatementGeographicalAxis_04511CB093243C09889AB4CBF1F0B566" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Geographical [Axis] </link:label>
<link:label id="lab_us-gaap_StatementGeographicalAxis_04511CB093243C09889AB4CBF1F0B566_label_en-US" xlink:label="lab_us-gaap_StatementGeographicalAxis_04511CB093243C09889AB4CBF1F0B566" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Geographical [Axis] </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_StatementGeographicalAxis" xlink:label="loc_us-gaap_StatementGeographicalAxis_04511CB093243C09889AB4CBF1F0B566" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_StatementGeographicalAxis_04511CB093243C09889AB4CBF1F0B566" xlink:to="lab_us-gaap_StatementGeographicalAxis_04511CB093243C09889AB4CBF1F0B566" xlink:type="arc"/>
<link:label id="lab_us-gaap_SegmentGeographicalDomain_8ADA1F5841ED5208D937B4CBF1F0093E_terseLabel_en-US" xlink:label="lab_us-gaap_SegmentGeographicalDomain_8ADA1F5841ED5208D937B4CBF1F0093E" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Geographical [Domain] </link:label>
<link:label id="lab_us-gaap_SegmentGeographicalDomain_8ADA1F5841ED5208D937B4CBF1F0093E_label_en-US" xlink:label="lab_us-gaap_SegmentGeographicalDomain_8ADA1F5841ED5208D937B4CBF1F0093E" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Geographical [Domain] </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_SegmentGeographicalDomain" xlink:label="loc_us-gaap_SegmentGeographicalDomain_8ADA1F5841ED5208D937B4CBF1F0093E" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_SegmentGeographicalDomain_8ADA1F5841ED5208D937B4CBF1F0093E" xlink:to="lab_us-gaap_SegmentGeographicalDomain_8ADA1F5841ED5208D937B4CBF1F0093E" xlink:type="arc"/>
<link:label id="lab_it_UnitedStatesAndCanadaMember_905EDAF18DC30CEBCE7EB4CBF1F01B0C_terseLabel_en-US" xlink:label="lab_it_UnitedStatesAndCanadaMember_905EDAF18DC30CEBCE7EB4CBF1F01B0C" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> United States and Canada </link:label>
<link:label id="lab_it_UnitedStatesAndCanadaMember_905EDAF18DC30CEBCE7EB4CBF1F01B0C_label_en-US" xlink:label="lab_it_UnitedStatesAndCanadaMember_905EDAF18DC30CEBCE7EB4CBF1F01B0C" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> United States And Canada [Member] </link:label>
<link:label id="lab_it_UnitedStatesAndCanadaMember_905EDAF18DC30CEBCE7EB4CBF1F01B0C_documentation_en-US" xlink:label="lab_it_UnitedStatesAndCanadaMember_905EDAF18DC30CEBCE7EB4CBF1F01B0C" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US"> -- None. No documentation exists for this element. -- </link:label>
<link:loc xlink:href="it-20161231.xsd#it_UnitedStatesAndCanadaMember" xlink:label="loc_it_UnitedStatesAndCanadaMember_905EDAF18DC30CEBCE7EB4CBF1F01B0C" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_it_UnitedStatesAndCanadaMember_905EDAF18DC30CEBCE7EB4CBF1F01B0C" xlink:to="lab_it_UnitedStatesAndCanadaMember_905EDAF18DC30CEBCE7EB4CBF1F01B0C" xlink:type="arc"/>
<link:label id="lab_it_EuropeMiddleEastAfricaMember_3AD19651EFB293353C9DB4CBF1F01BE1_terseLabel_en-US" xlink:label="lab_it_EuropeMiddleEastAfricaMember_3AD19651EFB293353C9DB4CBF1F01BE1" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Europe, Middle East and Africa </link:label>
<link:label id="lab_it_EuropeMiddleEastAfricaMember_3AD19651EFB293353C9DB4CBF1F01BE1_label_en-US" xlink:label="lab_it_EuropeMiddleEastAfricaMember_3AD19651EFB293353C9DB4CBF1F01BE1" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Europe Middle East Africa [Member] </link:label>
<link:label id="lab_it_EuropeMiddleEastAfricaMember_3AD19651EFB293353C9DB4CBF1F01BE1_documentation_en-US" xlink:label="lab_it_EuropeMiddleEastAfricaMember_3AD19651EFB293353C9DB4CBF1F01BE1" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US"> -- None. No documentation exists for this element. -- </link:label>
<link:loc xlink:href="it-20161231.xsd#it_EuropeMiddleEastAfricaMember" xlink:label="loc_it_EuropeMiddleEastAfricaMember_3AD19651EFB293353C9DB4CBF1F01BE1" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_it_EuropeMiddleEastAfricaMember_3AD19651EFB293353C9DB4CBF1F01BE1" xlink:to="lab_it_EuropeMiddleEastAfricaMember_3AD19651EFB293353C9DB4CBF1F01BE1" xlink:type="arc"/>
<link:label id="lab_it_OtherInternationalMember_E9668A9F230337E87BF2B4CBF1F0C901_terseLabel_en-US" xlink:label="lab_it_OtherInternationalMember_E9668A9F230337E87BF2B4CBF1F0C901" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Other International </link:label>
<link:label id="lab_it_OtherInternationalMember_E9668A9F230337E87BF2B4CBF1F0C901_label_en-US" xlink:label="lab_it_OtherInternationalMember_E9668A9F230337E87BF2B4CBF1F0C901" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Other International [Member] </link:label>
<link:label id="lab_it_OtherInternationalMember_E9668A9F230337E87BF2B4CBF1F0C901_documentation_en-US" xlink:label="lab_it_OtherInternationalMember_E9668A9F230337E87BF2B4CBF1F0C901" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US"> -- None. No documentation exists for this element. -- </link:label>
<link:loc xlink:href="it-20161231.xsd#it_OtherInternationalMember" xlink:label="loc_it_OtherInternationalMember_E9668A9F230337E87BF2B4CBF1F0C901" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_it_OtherInternationalMember_E9668A9F230337E87BF2B4CBF1F0C901" xlink:to="lab_it_OtherInternationalMember_E9668A9F230337E87BF2B4CBF1F0C901" xlink:type="arc"/>
<link:label id="lab_us-gaap_RevenuesFromExternalCustomersAndLongLivedAssetsLineItems_9EB27C8B7134F5BA7948B4CBF1F02D60_terseLabel_en-US" xlink:label="lab_us-gaap_RevenuesFromExternalCustomersAndLongLivedAssetsLineItems_9EB27C8B7134F5BA7948B4CBF1F02D60" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Revenues from External Customers and Long-Lived Assets [Line Items] </link:label>
<link:label id="lab_us-gaap_RevenuesFromExternalCustomersAndLongLivedAssetsLineItems_9EB27C8B7134F5BA7948B4CBF1F02D60_label_en-US" xlink:label="lab_us-gaap_RevenuesFromExternalCustomersAndLongLivedAssetsLineItems_9EB27C8B7134F5BA7948B4CBF1F02D60" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Revenues from External Customers and Long-Lived Assets [Line Items] </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_RevenuesFromExternalCustomersAndLongLivedAssetsLineItems" xlink:label="loc_us-gaap_RevenuesFromExternalCustomersAndLongLivedAssetsLineItems_9EB27C8B7134F5BA7948B4CBF1F02D60" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_RevenuesFromExternalCustomersAndLongLivedAssetsLineItems_9EB27C8B7134F5BA7948B4CBF1F02D60" xlink:to="lab_us-gaap_RevenuesFromExternalCustomersAndLongLivedAssetsLineItems_9EB27C8B7134F5BA7948B4CBF1F02D60" xlink:type="arc"/>
<link:label id="lab_it_RevenuesAbstract0_FE8DEC3CEC3080672739B4CBF1F093F4_terseLabel_en-US" xlink:label="lab_it_RevenuesAbstract0_FE8DEC3CEC3080672739B4CBF1F093F4" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Revenues: </link:label>
<link:label id="lab_it_RevenuesAbstract0_FE8DEC3CEC3080672739B4CBF1F093F4_label_en-US" xlink:label="lab_it_RevenuesAbstract0_FE8DEC3CEC3080672739B4CBF1F093F4" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Revenues: [Abstract]0 </link:label>
<link:label id="lab_it_RevenuesAbstract0_FE8DEC3CEC3080672739B4CBF1F093F4_documentation_en-US" xlink:label="lab_it_RevenuesAbstract0_FE8DEC3CEC3080672739B4CBF1F093F4" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US"> -- None. No documentation exists for this element. -- </link:label>
<link:loc xlink:href="it-20161231.xsd#it_RevenuesAbstract0" xlink:label="loc_it_RevenuesAbstract0_FE8DEC3CEC3080672739B4CBF1F093F4" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_it_RevenuesAbstract0_FE8DEC3CEC3080672739B4CBF1F093F4" xlink:to="lab_it_RevenuesAbstract0_FE8DEC3CEC3080672739B4CBF1F093F4" xlink:type="arc"/>
<link:label id="lab_us-gaap_SalesRevenueNet_D9F59C059F3C4FCF2824B4CBF1F09FCD_terseLabel_en-US" xlink:label="lab_us-gaap_SalesRevenueNet_D9F59C059F3C4FCF2824B4CBF1F09FCD" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Revenues </link:label>
<link:label id="lab_us-gaap_SalesRevenueNet_D9F59C059F3C4FCF2824B4CBF1F09FCD_label_en-US" xlink:label="lab_us-gaap_SalesRevenueNet_D9F59C059F3C4FCF2824B4CBF1F09FCD" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Revenue, Net </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_SalesRevenueNet" xlink:label="loc_us-gaap_SalesRevenueNet_D9F59C059F3C4FCF2824B4CBF1F09FCD" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_SalesRevenueNet_D9F59C059F3C4FCF2824B4CBF1F09FCD" xlink:to="lab_us-gaap_SalesRevenueNet_D9F59C059F3C4FCF2824B4CBF1F09FCD" xlink:type="arc"/>
<link:label id="lab_it_LongLivedAssets1Abstract_AB64FF0721426E33DD71B4CBF1F085AF_terseLabel_en-US" xlink:label="lab_it_LongLivedAssets1Abstract_AB64FF0721426E33DD71B4CBF1F085AF" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Long-lived assets: </link:label>
<link:label id="lab_it_LongLivedAssets1Abstract_AB64FF0721426E33DD71B4CBF1F085AF_label_en-US" xlink:label="lab_it_LongLivedAssets1Abstract_AB64FF0721426E33DD71B4CBF1F085AF" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Long-lived assets: (1) [Abstract] </link:label>
<link:label id="lab_it_LongLivedAssets1Abstract_AB64FF0721426E33DD71B4CBF1F085AF_documentation_en-US" xlink:label="lab_it_LongLivedAssets1Abstract_AB64FF0721426E33DD71B4CBF1F085AF" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US"> -- None. No documentation exists for this element. -- </link:label>
<link:loc xlink:href="it-20161231.xsd#it_LongLivedAssets1Abstract" xlink:label="loc_it_LongLivedAssets1Abstract_AB64FF0721426E33DD71B4CBF1F085AF" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_it_LongLivedAssets1Abstract_AB64FF0721426E33DD71B4CBF1F085AF" xlink:to="lab_it_LongLivedAssets1Abstract_AB64FF0721426E33DD71B4CBF1F085AF" xlink:type="arc"/>
<link:label id="lab_us-gaap_AssetsNoncurrent_C0021C149BE1015B32B5B4CBF1F0300A_terseLabel_en-US" xlink:label="lab_us-gaap_AssetsNoncurrent_C0021C149BE1015B32B5B4CBF1F0300A" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Long-lived assets </link:label>
<link:label id="lab_us-gaap_AssetsNoncurrent_C0021C149BE1015B32B5B4CBF1F0300A_label_en-US" xlink:label="lab_us-gaap_AssetsNoncurrent_C0021C149BE1015B32B5B4CBF1F0300A" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Assets, Noncurrent </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_AssetsNoncurrent" xlink:label="loc_us-gaap_AssetsNoncurrent_C0021C149BE1015B32B5B4CBF1F0300A" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_AssetsNoncurrent_C0021C149BE1015B32B5B4CBF1F0300A" xlink:to="lab_us-gaap_AssetsNoncurrent_C0021C149BE1015B32B5B4CBF1F0300A" xlink:type="arc"/>
<link:label id="lab_us-gaap_EarningsPerShareTextBlock_FC93949CE5F82B006E19E53BFD2662C1_terseLabel_en-US" xlink:label="lab_us-gaap_EarningsPerShareTextBlock_FC93949CE5F82B006E19E53BFD2662C1" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> COMPUTATION OF EARNINGS PER SHARE </link:label>
<link:label id="lab_us-gaap_EarningsPerShareTextBlock_FC93949CE5F82B006E19E53BFD2662C1_label_en-US" xlink:label="lab_us-gaap_EarningsPerShareTextBlock_FC93949CE5F82B006E19E53BFD2662C1" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Earnings Per Share [Text Block] </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_EarningsPerShareTextBlock" xlink:label="loc_us-gaap_EarningsPerShareTextBlock_FC93949CE5F82B006E19E53BFD2662C1" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_EarningsPerShareTextBlock_FC93949CE5F82B006E19E53BFD2662C1" xlink:to="lab_us-gaap_EarningsPerShareTextBlock_FC93949CE5F82B006E19E53BFD2662C1" xlink:type="arc"/>
<link:label id="lab_us-gaap_DebtDisclosureAbstract_B8B37FFDC0D9DC7556C14797E137010F_label_en-US" xlink:label="lab_us-gaap_DebtDisclosureAbstract_B8B37FFDC0D9DC7556C14797E137010F" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Debt Disclosure [Abstract] </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_DebtDisclosureAbstract" xlink:label="loc_us-gaap_DebtDisclosureAbstract_B8B37FFDC0D9DC7556C14797E137010F" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DebtDisclosureAbstract_B8B37FFDC0D9DC7556C14797E137010F" xlink:to="lab_us-gaap_DebtDisclosureAbstract_B8B37FFDC0D9DC7556C14797E137010F" xlink:type="arc"/>
<link:label id="lab_us-gaap_ScheduleOfDebtTableTextBlock_33EA70EEF862CCC31C744797E1377752_terseLabel_en-US" xlink:label="lab_us-gaap_ScheduleOfDebtTableTextBlock_33EA70EEF862CCC31C744797E1377752" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Schedule of Debt </link:label>
<link:label id="lab_us-gaap_ScheduleOfDebtTableTextBlock_33EA70EEF862CCC31C744797E1377752_label_en-US" xlink:label="lab_us-gaap_ScheduleOfDebtTableTextBlock_33EA70EEF862CCC31C744797E1377752" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Schedule of Debt [Table Text Block] </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ScheduleOfDebtTableTextBlock" xlink:label="loc_us-gaap_ScheduleOfDebtTableTextBlock_33EA70EEF862CCC31C744797E1377752" xlink:type="locator"/>
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<link:label id="lab_us-gaap_FairValueDisclosuresAbstract_1BD35E169185DB488A92E53BFB238179_label_en-US" xlink:label="lab_us-gaap_FairValueDisclosuresAbstract_1BD35E169185DB488A92E53BFB238179" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Fair Value Disclosures [Abstract] </link:label>
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<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ComputerSoftwareIntangibleAssetMember_E2A1CFC8453EF5E7F26A3FEE5842E898" xlink:to="lab_us-gaap_ComputerSoftwareIntangibleAssetMember_E2A1CFC8453EF5E7F26A3FEE5842E898" xlink:type="arc"/>
<link:label id="lab_it_EquipmentAndFurnitureMember_1ABD93517F7DCFE1A8FE3FEE58422C34_terseLabel_en-US" xlink:label="lab_it_EquipmentAndFurnitureMember_1ABD93517F7DCFE1A8FE3FEE58422C34" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Furniture and equipment </link:label>
<link:label id="lab_it_EquipmentAndFurnitureMember_1ABD93517F7DCFE1A8FE3FEE58422C34_label_en-US" xlink:label="lab_it_EquipmentAndFurnitureMember_1ABD93517F7DCFE1A8FE3FEE58422C34" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Equipment And Furniture [Member] </link:label>
<link:label id="lab_it_EquipmentAndFurnitureMember_1ABD93517F7DCFE1A8FE3FEE58422C34_documentation_en-US" xlink:label="lab_it_EquipmentAndFurnitureMember_1ABD93517F7DCFE1A8FE3FEE58422C34" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US"> Equipment and Furniture [Member] </link:label>
<link:loc xlink:href="it-20161231.xsd#it_EquipmentAndFurnitureMember" xlink:label="loc_it_EquipmentAndFurnitureMember_1ABD93517F7DCFE1A8FE3FEE58422C34" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_it_EquipmentAndFurnitureMember_1ABD93517F7DCFE1A8FE3FEE58422C34" xlink:to="lab_it_EquipmentAndFurnitureMember_1ABD93517F7DCFE1A8FE3FEE58422C34" xlink:type="arc"/>
<link:label id="lab_us-gaap_LeaseholdImprovementsMember_4869CB7792FFDD55C66D3FEE5842D1F2_terseLabel_en-US" xlink:label="lab_us-gaap_LeaseholdImprovementsMember_4869CB7792FFDD55C66D3FEE5842D1F2" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Leasehold improvements </link:label>
<link:label id="lab_us-gaap_LeaseholdImprovementsMember_4869CB7792FFDD55C66D3FEE5842D1F2_label_en-US" xlink:label="lab_us-gaap_LeaseholdImprovementsMember_4869CB7792FFDD55C66D3FEE5842D1F2" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Leasehold Improvements [Member] </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_LeaseholdImprovementsMember" xlink:label="loc_us-gaap_LeaseholdImprovementsMember_4869CB7792FFDD55C66D3FEE5842D1F2" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_LeaseholdImprovementsMember_4869CB7792FFDD55C66D3FEE5842D1F2" xlink:to="lab_us-gaap_LeaseholdImprovementsMember_4869CB7792FFDD55C66D3FEE5842D1F2" xlink:type="arc"/>
<link:label id="lab_us-gaap_MinimumMember_AFA6D12831C232C333FD3FEE5842F48F_terseLabel_en-US" xlink:label="lab_us-gaap_MinimumMember_AFA6D12831C232C333FD3FEE5842F48F" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Minimum </link:label>
<link:label id="lab_us-gaap_MinimumMember_AFA6D12831C232C333FD3FEE5842F48F_label_en-US" xlink:label="lab_us-gaap_MinimumMember_AFA6D12831C232C333FD3FEE5842F48F" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Minimum [Member] </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_MinimumMember" xlink:label="loc_us-gaap_MinimumMember_AFA6D12831C232C333FD3FEE5842F48F" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_MinimumMember_AFA6D12831C232C333FD3FEE5842F48F" xlink:to="lab_us-gaap_MinimumMember_AFA6D12831C232C333FD3FEE5842F48F" xlink:type="arc"/>
<link:label id="lab_us-gaap_PropertyPlantAndEquipmentLineItems_1E030BA80D7C7B7E18743FEE58427B6F_terseLabel_en-US" xlink:label="lab_us-gaap_PropertyPlantAndEquipmentLineItems_1E030BA80D7C7B7E18743FEE58427B6F" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Property, Plant and Equipment [Line Items] </link:label>
<link:label id="lab_us-gaap_PropertyPlantAndEquipmentLineItems_1E030BA80D7C7B7E18743FEE58427B6F_label_en-US" xlink:label="lab_us-gaap_PropertyPlantAndEquipmentLineItems_1E030BA80D7C7B7E18743FEE58427B6F" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Property, Plant and Equipment [Line Items] </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_PropertyPlantAndEquipmentLineItems" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentLineItems_1E030BA80D7C7B7E18743FEE58427B6F" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_1E030BA80D7C7B7E18743FEE58427B6F" xlink:to="lab_us-gaap_PropertyPlantAndEquipmentLineItems_1E030BA80D7C7B7E18743FEE58427B6F" xlink:type="arc"/>
<link:label id="lab_us-gaap_OperatingLeasesRentExpenseNet_552D56B1F72683D4EA7D3FEE5878BDDA_terseLabel_en-US" xlink:label="lab_us-gaap_OperatingLeasesRentExpenseNet_552D56B1F72683D4EA7D3FEE5878BDDA" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Rent expense </link:label>
<link:label id="lab_us-gaap_OperatingLeasesRentExpenseNet_552D56B1F72683D4EA7D3FEE5878BDDA_label_en-US" xlink:label="lab_us-gaap_OperatingLeasesRentExpenseNet_552D56B1F72683D4EA7D3FEE5878BDDA" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Operating Leases, Rent Expense, Net </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_OperatingLeasesRentExpenseNet" xlink:label="loc_us-gaap_OperatingLeasesRentExpenseNet_552D56B1F72683D4EA7D3FEE5878BDDA" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_OperatingLeasesRentExpenseNet_552D56B1F72683D4EA7D3FEE5878BDDA" xlink:to="lab_us-gaap_OperatingLeasesRentExpenseNet_552D56B1F72683D4EA7D3FEE5878BDDA" xlink:type="arc"/>
<link:label id="lab_us-gaap_PropertyPlantAndEquipmentUsefulLife_C282992948EF245527613FEE587A554B_terseLabel_en-US" xlink:label="lab_us-gaap_PropertyPlantAndEquipmentUsefulLife_C282992948EF245527613FEE587A554B" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Useful Life </link:label>
<link:label id="lab_us-gaap_PropertyPlantAndEquipmentUsefulLife_C282992948EF245527613FEE587A554B_label_en-US" xlink:label="lab_us-gaap_PropertyPlantAndEquipmentUsefulLife_C282992948EF245527613FEE587A554B" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Property, Plant and Equipment, Useful Life </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_PropertyPlantAndEquipmentUsefulLife" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentUsefulLife_C282992948EF245527613FEE587A554B" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentUsefulLife_C282992948EF245527613FEE587A554B" xlink:to="lab_us-gaap_PropertyPlantAndEquipmentUsefulLife_C282992948EF245527613FEE587A554B" xlink:type="arc"/>
<link:label id="lab_us-gaap_PropertyPlantAndEquipmentGross_45164781D63A630A2AD03FEE587A1C00_terseLabel_en-US" xlink:label="lab_us-gaap_PropertyPlantAndEquipmentGross_45164781D63A630A2AD03FEE587A1C00" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Property, equipment and leasehold improvements, gross </link:label>
<link:label id="lab_us-gaap_PropertyPlantAndEquipmentGross_45164781D63A630A2AD03FEE587A1C00_label_en-US" xlink:label="lab_us-gaap_PropertyPlantAndEquipmentGross_45164781D63A630A2AD03FEE587A1C00" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Property, Plant and Equipment, Gross </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_PropertyPlantAndEquipmentGross" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentGross_45164781D63A630A2AD03FEE587A1C00" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentGross_45164781D63A630A2AD03FEE587A1C00" xlink:to="lab_us-gaap_PropertyPlantAndEquipmentGross_45164781D63A630A2AD03FEE587A1C00" xlink:type="arc"/>
<link:label id="lab_us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment_AD825162BA70F05C1BE93FEE587A032B_negatedTerseLabel_en-US" xlink:label="lab_us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment_AD825162BA70F05C1BE93FEE587A032B" xlink:role="http://www.xbrl.org/2009/role/negatedTerseLabel" xlink:type="resource" xml:lang="en-US"> Less — accumulated depreciation and amortization </link:label>
<link:label id="lab_us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment_AD825162BA70F05C1BE93FEE587A032B_label_en-US" xlink:label="lab_us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment_AD825162BA70F05C1BE93FEE587A032B" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment" xlink:label="loc_us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment_AD825162BA70F05C1BE93FEE587A032B" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment_AD825162BA70F05C1BE93FEE587A032B" xlink:to="lab_us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment_AD825162BA70F05C1BE93FEE587A032B" xlink:type="arc"/>
<link:label id="lab_us-gaap_PropertyPlantAndEquipmentNet_ABFA318F7DBBC18494923FEE587A6A5D_totalLabel_en-US" xlink:label="lab_us-gaap_PropertyPlantAndEquipmentNet_ABFA318F7DBBC18494923FEE587A6A5D" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:type="resource" xml:lang="en-US"> Property, equipment and leasehold improvements, net </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_PropertyPlantAndEquipmentNet" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentNet_ABFA318F7DBBC18494923FEE587A6A5D" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentNet_ABFA318F7DBBC18494923FEE587A6A5D" xlink:to="lab_us-gaap_PropertyPlantAndEquipmentNet_ABFA318F7DBBC18494923FEE587A6A5D" xlink:type="arc"/>
<link:label id="lab_us-gaap_PayablesAndAccrualsAbstract_2A122A707E40299B8C5CE53BFCC0D871_label_en-US" xlink:label="lab_us-gaap_PayablesAndAccrualsAbstract_2A122A707E40299B8C5CE53BFCC0D871" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Payables and Accruals [Abstract] </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_PayablesAndAccrualsAbstract" xlink:label="loc_us-gaap_PayablesAndAccrualsAbstract_2A122A707E40299B8C5CE53BFCC0D871" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_PayablesAndAccrualsAbstract_2A122A707E40299B8C5CE53BFCC0D871" xlink:to="lab_us-gaap_PayablesAndAccrualsAbstract_2A122A707E40299B8C5CE53BFCC0D871" xlink:type="arc"/>
<link:label id="lab_us-gaap_AccountsPayableAccruedLiabilitiesAndOtherLiabilitiesDisclosureCurrentTextBlock_5F15F2EE2D44E6364FCBE53BFCC09049_terseLabel_en-US" xlink:label="lab_us-gaap_AccountsPayableAccruedLiabilitiesAndOtherLiabilitiesDisclosureCurrentTextBlock_5F15F2EE2D44E6364FCBE53BFCC09049" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> ACCOUNTS PAYABLE, ACCRUED, AND OTHER LIABILITIES </link:label>
<link:label id="lab_us-gaap_AccountsPayableAccruedLiabilitiesAndOtherLiabilitiesDisclosureCurrentTextBlock_5F15F2EE2D44E6364FCBE53BFCC09049_label_en-US" xlink:label="lab_us-gaap_AccountsPayableAccruedLiabilitiesAndOtherLiabilitiesDisclosureCurrentTextBlock_5F15F2EE2D44E6364FCBE53BFCC09049" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Accounts Payable, Accrued Liabilities, and Other Liabilities Disclosure, Current [Text Block] </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_AccountsPayableAccruedLiabilitiesAndOtherLiabilitiesDisclosureCurrentTextBlock" xlink:label="loc_us-gaap_AccountsPayableAccruedLiabilitiesAndOtherLiabilitiesDisclosureCurrentTextBlock_5F15F2EE2D44E6364FCBE53BFCC09049" xlink:type="locator"/>
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<link:label id="lab_it_IncomeTaxTable_15F7F7170E17B6A028536196542A99CB_terseLabel_en-US" xlink:label="lab_it_IncomeTaxTable_15F7F7170E17B6A028536196542A99CB" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Income Tax [Table] </link:label>
<link:label id="lab_it_IncomeTaxTable_15F7F7170E17B6A028536196542A99CB_label_en-US" xlink:label="lab_it_IncomeTaxTable_15F7F7170E17B6A028536196542A99CB" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Income Tax [Table] </link:label>
<link:label id="lab_it_IncomeTaxTable_15F7F7170E17B6A028536196542A99CB_documentation_en-US" xlink:label="lab_it_IncomeTaxTable_15F7F7170E17B6A028536196542A99CB" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US"> Income Tax [Table] </link:label>
<link:loc xlink:href="it-20161231.xsd#it_IncomeTaxTable" xlink:label="loc_it_IncomeTaxTable_15F7F7170E17B6A028536196542A99CB" xlink:type="locator"/>
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<link:label id="lab_us-gaap_BalanceSheetLocationAxis_400D4D5F22829D5230326196542BD3A2_terseLabel_en-US" xlink:label="lab_us-gaap_BalanceSheetLocationAxis_400D4D5F22829D5230326196542BD3A2" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Balance Sheet Location [Axis] </link:label>
<link:label id="lab_us-gaap_BalanceSheetLocationAxis_400D4D5F22829D5230326196542BD3A2_label_en-US" xlink:label="lab_us-gaap_BalanceSheetLocationAxis_400D4D5F22829D5230326196542BD3A2" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Balance Sheet Location [Axis] </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_BalanceSheetLocationAxis" xlink:label="loc_us-gaap_BalanceSheetLocationAxis_400D4D5F22829D5230326196542BD3A2" xlink:type="locator"/>
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<link:label id="lab_us-gaap_BalanceSheetLocationDomain_D45E655F2968B102C7096196542B3F4C_terseLabel_en-US" xlink:label="lab_us-gaap_BalanceSheetLocationDomain_D45E655F2968B102C7096196542B3F4C" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Balance Sheet Location [Domain] </link:label>
<link:label id="lab_us-gaap_BalanceSheetLocationDomain_D45E655F2968B102C7096196542B3F4C_label_en-US" xlink:label="lab_us-gaap_BalanceSheetLocationDomain_D45E655F2968B102C7096196542B3F4C" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Balance Sheet Location [Domain] </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_BalanceSheetLocationDomain" xlink:label="loc_us-gaap_BalanceSheetLocationDomain_D45E655F2968B102C7096196542B3F4C" xlink:type="locator"/>
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<link:label id="lab_us-gaap_OtherAssetsMember_46591C9331470D85618F6196542BADF2_terseLabel_en-US" xlink:label="lab_us-gaap_OtherAssetsMember_46591C9331470D85618F6196542BADF2" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Other assets </link:label>
<link:label id="lab_us-gaap_OtherAssetsMember_46591C9331470D85618F6196542BADF2_label_en-US" xlink:label="lab_us-gaap_OtherAssetsMember_46591C9331470D85618F6196542BADF2" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Other Assets [Member] </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_OtherAssetsMember" xlink:label="loc_us-gaap_OtherAssetsMember_46591C9331470D85618F6196542BADF2" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_OtherAssetsMember_46591C9331470D85618F6196542BADF2" xlink:to="lab_us-gaap_OtherAssetsMember_46591C9331470D85618F6196542BADF2" xlink:type="arc"/>
<link:label id="lab_us-gaap_OtherLiabilitiesMember_B45321BAB6C66AB15B936196542CE167_terseLabel_en-US" xlink:label="lab_us-gaap_OtherLiabilitiesMember_B45321BAB6C66AB15B936196542CE167" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Other liabilities </link:label>
<link:label id="lab_us-gaap_OtherLiabilitiesMember_B45321BAB6C66AB15B936196542CE167_label_en-US" xlink:label="lab_us-gaap_OtherLiabilitiesMember_B45321BAB6C66AB15B936196542CE167" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Other Liabilities [Member] </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_OtherLiabilitiesMember" xlink:label="loc_us-gaap_OtherLiabilitiesMember_B45321BAB6C66AB15B936196542CE167" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_OtherLiabilitiesMember_B45321BAB6C66AB15B936196542CE167" xlink:to="lab_us-gaap_OtherLiabilitiesMember_B45321BAB6C66AB15B936196542CE167" xlink:type="arc"/>
<link:label id="lab_it_PeriodAxis_F531B63E308E31B9E4386196542CABEF_terseLabel_en-US" xlink:label="lab_it_PeriodAxis_F531B63E308E31B9E4386196542CABEF" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Period [Axis] </link:label>
<link:label id="lab_it_PeriodAxis_F531B63E308E31B9E4386196542CABEF_label_en-US" xlink:label="lab_it_PeriodAxis_F531B63E308E31B9E4386196542CABEF" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Period [Axis] </link:label>
<link:label id="lab_it_PeriodAxis_F531B63E308E31B9E4386196542CABEF_documentation_en-US" xlink:label="lab_it_PeriodAxis_F531B63E308E31B9E4386196542CABEF" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US"> Period [Axis] </link:label>
<link:loc xlink:href="it-20161231.xsd#it_PeriodAxis" xlink:label="loc_it_PeriodAxis_F531B63E308E31B9E4386196542CABEF" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_it_PeriodAxis_F531B63E308E31B9E4386196542CABEF" xlink:to="lab_it_PeriodAxis_F531B63E308E31B9E4386196542CABEF" xlink:type="arc"/>
<link:label id="lab_it_PeriodDomain_64B8BAADCA681267A7E86196542CF768_terseLabel_en-US" xlink:label="lab_it_PeriodDomain_64B8BAADCA681267A7E86196542CF768" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Period [Domain] </link:label>
<link:label id="lab_it_PeriodDomain_64B8BAADCA681267A7E86196542CF768_label_en-US" xlink:label="lab_it_PeriodDomain_64B8BAADCA681267A7E86196542CF768" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Period [Domain] </link:label>
<link:label id="lab_it_PeriodDomain_64B8BAADCA681267A7E86196542CF768_documentation_en-US" xlink:label="lab_it_PeriodDomain_64B8BAADCA681267A7E86196542CF768" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US"> -- None. No documentation exists for this element. -- </link:label>
<link:loc xlink:href="it-20161231.xsd#it_PeriodDomain" xlink:label="loc_it_PeriodDomain_64B8BAADCA681267A7E86196542CF768" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_it_PeriodDomain_64B8BAADCA681267A7E86196542CF768" xlink:to="lab_it_PeriodDomain_64B8BAADCA681267A7E86196542CF768" xlink:type="arc"/>
<link:label id="lab_it_ExpireWithinOneToFiveYearsMember_D643A4574B9B404250856196542C5077_terseLabel_en-US" xlink:label="lab_it_ExpireWithinOneToFiveYearsMember_D643A4574B9B404250856196542C5077" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Expire within one to five years </link:label>
<link:label id="lab_it_ExpireWithinOneToFiveYearsMember_D643A4574B9B404250856196542C5077_label_en-US" xlink:label="lab_it_ExpireWithinOneToFiveYearsMember_D643A4574B9B404250856196542C5077" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Expire Within One To Five Years [Member] </link:label>
<link:label id="lab_it_ExpireWithinOneToFiveYearsMember_D643A4574B9B404250856196542C5077_documentation_en-US" xlink:label="lab_it_ExpireWithinOneToFiveYearsMember_D643A4574B9B404250856196542C5077" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US"> -- None. No documentation exists for this element. -- </link:label>
<link:loc xlink:href="it-20161231.xsd#it_ExpireWithinOneToFiveYearsMember" xlink:label="loc_it_ExpireWithinOneToFiveYearsMember_D643A4574B9B404250856196542C5077" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_it_ExpireWithinOneToFiveYearsMember_D643A4574B9B404250856196542C5077" xlink:to="lab_it_ExpireWithinOneToFiveYearsMember_D643A4574B9B404250856196542C5077" xlink:type="arc"/>
<link:label id="lab_it_ExpireWithinSixToFifteenYearsMember_4F08B422C37701BE37A96196542C5AFA_terseLabel_en-US" xlink:label="lab_it_ExpireWithinSixToFifteenYearsMember_4F08B422C37701BE37A96196542C5AFA" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Expire within six to fifteen years </link:label>
<link:label id="lab_it_ExpireWithinSixToFifteenYearsMember_4F08B422C37701BE37A96196542C5AFA_label_en-US" xlink:label="lab_it_ExpireWithinSixToFifteenYearsMember_4F08B422C37701BE37A96196542C5AFA" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Expire Within Six To Fifteen Years [Member] </link:label>
<link:label id="lab_it_ExpireWithinSixToFifteenYearsMember_4F08B422C37701BE37A96196542C5AFA_documentation_en-US" xlink:label="lab_it_ExpireWithinSixToFifteenYearsMember_4F08B422C37701BE37A96196542C5AFA" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US"> -- None. No documentation exists for this element. -- </link:label>
<link:loc xlink:href="it-20161231.xsd#it_ExpireWithinSixToFifteenYearsMember" xlink:label="loc_it_ExpireWithinSixToFifteenYearsMember_4F08B422C37701BE37A96196542C5AFA" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_it_ExpireWithinSixToFifteenYearsMember_4F08B422C37701BE37A96196542C5AFA" xlink:to="lab_it_ExpireWithinSixToFifteenYearsMember_4F08B422C37701BE37A96196542C5AFA" xlink:type="arc"/>
<link:label id="lab_it_ExpireOverNextTwentyYearsMember_FAAA44B327560B16DB2D6196542CBBBC_terseLabel_en-US" xlink:label="lab_it_ExpireOverNextTwentyYearsMember_FAAA44B327560B16DB2D6196542CBBBC" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Expire over next twenty years </link:label>
<link:label id="lab_it_ExpireOverNextTwentyYearsMember_FAAA44B327560B16DB2D6196542CBBBC_label_en-US" xlink:label="lab_it_ExpireOverNextTwentyYearsMember_FAAA44B327560B16DB2D6196542CBBBC" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Expire Over Next Twenty Years [Member] </link:label>
<link:label id="lab_it_ExpireOverNextTwentyYearsMember_FAAA44B327560B16DB2D6196542CBBBC_documentation_en-US" xlink:label="lab_it_ExpireOverNextTwentyYearsMember_FAAA44B327560B16DB2D6196542CBBBC" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US"> -- None. No documentation exists for this element. -- </link:label>
<link:loc xlink:href="it-20161231.xsd#it_ExpireOverNextTwentyYearsMember" xlink:label="loc_it_ExpireOverNextTwentyYearsMember_FAAA44B327560B16DB2D6196542CBBBC" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_it_ExpireOverNextTwentyYearsMember_FAAA44B327560B16DB2D6196542CBBBC" xlink:to="lab_it_ExpireOverNextTwentyYearsMember_FAAA44B327560B16DB2D6196542CBBBC" xlink:type="arc"/>
<link:label id="lab_it_CarriedForwardIndefinitelyMember_BA8D7F06C67B543D04416196542C0D5E_terseLabel_en-US" xlink:label="lab_it_CarriedForwardIndefinitelyMember_BA8D7F06C67B543D04416196542C0D5E" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Carried forward indefinitely </link:label>
<link:label id="lab_it_CarriedForwardIndefinitelyMember_BA8D7F06C67B543D04416196542C0D5E_label_en-US" xlink:label="lab_it_CarriedForwardIndefinitelyMember_BA8D7F06C67B543D04416196542C0D5E" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Carried Forward Indefinitely [Member] </link:label>
<link:label id="lab_it_CarriedForwardIndefinitelyMember_BA8D7F06C67B543D04416196542C0D5E_documentation_en-US" xlink:label="lab_it_CarriedForwardIndefinitelyMember_BA8D7F06C67B543D04416196542C0D5E" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US"> -- None. No documentation exists for this element. -- </link:label>
<link:loc xlink:href="it-20161231.xsd#it_CarriedForwardIndefinitelyMember" xlink:label="loc_it_CarriedForwardIndefinitelyMember_BA8D7F06C67B543D04416196542C0D5E" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_it_CarriedForwardIndefinitelyMember_BA8D7F06C67B543D04416196542C0D5E" xlink:to="lab_it_CarriedForwardIndefinitelyMember_BA8D7F06C67B543D04416196542C0D5E" xlink:type="arc"/>
<link:label id="lab_us-gaap_IncomeTaxAuthorityAxis_3AFA8DC5862B5D735BF36196542C46CF_terseLabel_en-US" xlink:label="lab_us-gaap_IncomeTaxAuthorityAxis_3AFA8DC5862B5D735BF36196542C46CF" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Income Tax Authority [Axis] </link:label>
<link:label id="lab_us-gaap_IncomeTaxAuthorityAxis_3AFA8DC5862B5D735BF36196542C46CF_label_en-US" xlink:label="lab_us-gaap_IncomeTaxAuthorityAxis_3AFA8DC5862B5D735BF36196542C46CF" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Income Tax Authority [Axis] </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_IncomeTaxAuthorityAxis" xlink:label="loc_us-gaap_IncomeTaxAuthorityAxis_3AFA8DC5862B5D735BF36196542C46CF" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_IncomeTaxAuthorityAxis_3AFA8DC5862B5D735BF36196542C46CF" xlink:to="lab_us-gaap_IncomeTaxAuthorityAxis_3AFA8DC5862B5D735BF36196542C46CF" xlink:type="arc"/>
<link:label id="lab_us-gaap_IncomeTaxAuthorityDomain_D4D479CD6A78186ADA876196542C6F93_terseLabel_en-US" xlink:label="lab_us-gaap_IncomeTaxAuthorityDomain_D4D479CD6A78186ADA876196542C6F93" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Income Tax Authority [Domain] </link:label>
<link:label id="lab_us-gaap_IncomeTaxAuthorityDomain_D4D479CD6A78186ADA876196542C6F93_label_en-US" xlink:label="lab_us-gaap_IncomeTaxAuthorityDomain_D4D479CD6A78186ADA876196542C6F93" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Income Tax Authority [Domain] </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_IncomeTaxAuthorityDomain" xlink:label="loc_us-gaap_IncomeTaxAuthorityDomain_D4D479CD6A78186ADA876196542C6F93" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_IncomeTaxAuthorityDomain_D4D479CD6A78186ADA876196542C6F93" xlink:to="lab_us-gaap_IncomeTaxAuthorityDomain_D4D479CD6A78186ADA876196542C6F93" xlink:type="arc"/>
<link:label id="lab_us-gaap_StateAndLocalJurisdictionMember_0C94836FE4BD62F8ABDA6196542C6DDF_terseLabel_en-US" xlink:label="lab_us-gaap_StateAndLocalJurisdictionMember_0C94836FE4BD62F8ABDA6196542C6DDF" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> State and local jurisdiction </link:label>
<link:label id="lab_us-gaap_StateAndLocalJurisdictionMember_0C94836FE4BD62F8ABDA6196542C6DDF_label_en-US" xlink:label="lab_us-gaap_StateAndLocalJurisdictionMember_0C94836FE4BD62F8ABDA6196542C6DDF" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> State and Local Jurisdiction [Member] </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_StateAndLocalJurisdictionMember" xlink:label="loc_us-gaap_StateAndLocalJurisdictionMember_0C94836FE4BD62F8ABDA6196542C6DDF" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_StateAndLocalJurisdictionMember_0C94836FE4BD62F8ABDA6196542C6DDF" xlink:to="lab_us-gaap_StateAndLocalJurisdictionMember_0C94836FE4BD62F8ABDA6196542C6DDF" xlink:type="arc"/>
<link:label id="lab_us-gaap_NonUsMember_6C3E9BB8F657EB43A6826196542C5610_terseLabel_en-US" xlink:label="lab_us-gaap_NonUsMember_6C3E9BB8F657EB43A6826196542C5610" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Non US </link:label>
<link:label id="lab_us-gaap_NonUsMember_6C3E9BB8F657EB43A6826196542C5610_label_en-US" xlink:label="lab_us-gaap_NonUsMember_6C3E9BB8F657EB43A6826196542C5610" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Non-US [Member] </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_NonUsMember" xlink:label="loc_us-gaap_NonUsMember_6C3E9BB8F657EB43A6826196542C5610" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_NonUsMember_6C3E9BB8F657EB43A6826196542C5610" xlink:to="lab_us-gaap_NonUsMember_6C3E9BB8F657EB43A6826196542C5610" xlink:type="arc"/>
<link:label id="lab_it_FacilityAxis_4F82DB17855EFFB0630B6196542C36BA_terseLabel_en-US" xlink:label="lab_it_FacilityAxis_4F82DB17855EFFB0630B6196542C36BA" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Facility [Axis] </link:label>
<link:label id="lab_it_FacilityAxis_4F82DB17855EFFB0630B6196542C36BA_label_en-US" xlink:label="lab_it_FacilityAxis_4F82DB17855EFFB0630B6196542C36BA" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Facility [Axis] </link:label>
<link:label id="lab_it_FacilityAxis_4F82DB17855EFFB0630B6196542C36BA_documentation_en-US" xlink:label="lab_it_FacilityAxis_4F82DB17855EFFB0630B6196542C36BA" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US"> Facility [Axis] </link:label>
<link:loc xlink:href="it-20161231.xsd#it_FacilityAxis" xlink:label="loc_it_FacilityAxis_4F82DB17855EFFB0630B6196542C36BA" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_it_FacilityAxis_4F82DB17855EFFB0630B6196542C36BA" xlink:to="lab_it_FacilityAxis_4F82DB17855EFFB0630B6196542C36BA" xlink:type="arc"/>
<link:label id="lab_it_FacilityDomain_705D9C5268D5A0A64A576196542D9213_terseLabel_en-US" xlink:label="lab_it_FacilityDomain_705D9C5268D5A0A64A576196542D9213" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Facility [Domain] </link:label>
<link:label id="lab_it_FacilityDomain_705D9C5268D5A0A64A576196542D9213_label_en-US" xlink:label="lab_it_FacilityDomain_705D9C5268D5A0A64A576196542D9213" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Facility [Domain] </link:label>
<link:label id="lab_it_FacilityDomain_705D9C5268D5A0A64A576196542D9213_documentation_en-US" xlink:label="lab_it_FacilityDomain_705D9C5268D5A0A64A576196542D9213" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US"> -- None. No documentation exists for this element. -- </link:label>
<link:loc xlink:href="it-20161231.xsd#it_FacilityDomain" xlink:label="loc_it_FacilityDomain_705D9C5268D5A0A64A576196542D9213" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_it_FacilityDomain_705D9C5268D5A0A64A576196542D9213" xlink:to="lab_it_FacilityDomain_705D9C5268D5A0A64A576196542D9213" xlink:type="arc"/>
<link:label id="lab_it_StamfordMember_4F8C5549D986651EDDB96196542D1305_terseLabel_en-US" xlink:label="lab_it_StamfordMember_4F8C5549D986651EDDB96196542D1305" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Stamford </link:label>
<link:label id="lab_it_StamfordMember_4F8C5549D986651EDDB96196542D1305_label_en-US" xlink:label="lab_it_StamfordMember_4F8C5549D986651EDDB96196542D1305" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Stamford [Member] </link:label>
<link:label id="lab_it_StamfordMember_4F8C5549D986651EDDB96196542D1305_documentation_en-US" xlink:label="lab_it_StamfordMember_4F8C5549D986651EDDB96196542D1305" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US"> -- None. No documentation exists for this element. -- </link:label>
<link:loc xlink:href="it-20161231.xsd#it_StamfordMember" xlink:label="loc_it_StamfordMember_4F8C5549D986651EDDB96196542D1305" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_it_StamfordMember_4F8C5549D986651EDDB96196542D1305" xlink:to="lab_it_StamfordMember_4F8C5549D986651EDDB96196542D1305" xlink:type="arc"/>
<link:label id="lab_it_IncomeTaxLineItems_02F1FD64489C33BD037D6196542DE30B_terseLabel_en-US" xlink:label="lab_it_IncomeTaxLineItems_02F1FD64489C33BD037D6196542DE30B" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Income Tax [Line Items] </link:label>
<link:label id="lab_it_IncomeTaxLineItems_02F1FD64489C33BD037D6196542DE30B_label_en-US" xlink:label="lab_it_IncomeTaxLineItems_02F1FD64489C33BD037D6196542DE30B" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Income Tax [Line Items] </link:label>
<link:label id="lab_it_IncomeTaxLineItems_02F1FD64489C33BD037D6196542DE30B_documentation_en-US" xlink:label="lab_it_IncomeTaxLineItems_02F1FD64489C33BD037D6196542DE30B" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US"> [Line Items] Income Tax [Table] </link:label>
<link:loc xlink:href="it-20161231.xsd#it_IncomeTaxLineItems" xlink:label="loc_it_IncomeTaxLineItems_02F1FD64489C33BD037D6196542DE30B" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_it_IncomeTaxLineItems_02F1FD64489C33BD037D6196542DE30B" xlink:to="lab_it_IncomeTaxLineItems_02F1FD64489C33BD037D6196542DE30B" xlink:type="arc"/>
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<link:label id="lab_us-gaap_OperatingLossCarryforwards_B06646B364E06815B0756196542DB690_terseLabel_en-US" xlink:label="lab_us-gaap_OperatingLossCarryforwards_B06646B364E06815B0756196542DB690" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Operating loss carryforwards </link:label>
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<link:label id="lab_us-gaap_TaxCreditCarryforwardAmount_2556E07D00F264876E3B6196542D7FA2_terseLabel_en-US" xlink:label="lab_us-gaap_TaxCreditCarryforwardAmount_2556E07D00F264876E3B6196542D7FA2" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Tax credit carryforwards </link:label>
<link:label id="lab_us-gaap_TaxCreditCarryforwardAmount_2556E07D00F264876E3B6196542D7FA2_label_en-US" xlink:label="lab_us-gaap_TaxCreditCarryforwardAmount_2556E07D00F264876E3B6196542D7FA2" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Tax Credit Carryforward, Amount </link:label>
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<link:loc xlink:href="it-20161231.xsd#it_TaxCreditCarryforwardExpirationPeriod" xlink:label="loc_it_TaxCreditCarryforwardExpirationPeriod_943D707867A1497227A96196542D373A" xlink:type="locator"/>
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<link:label id="lab_us-gaap_DeferredTaxAssetsTaxCreditCarryforwardsForeign_BA7EA756CDDF51B66A016196543297DC_label_en-US" xlink:label="lab_us-gaap_DeferredTaxAssetsTaxCreditCarryforwardsForeign_BA7EA756CDDF51B66A016196543297DC" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Deferred Tax Assets, Tax Credit Carryforwards, Foreign </link:label>
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<link:label id="lab_it_EffectiveIncomeTaxRateReconciliationShareBasedCompensationExcessTaxBenefitAmount_0AA25E7CB4E4BED5C33F619654321344_terseLabel_en-US" xlink:label="lab_it_EffectiveIncomeTaxRateReconciliationShareBasedCompensationExcessTaxBenefitAmount_0AA25E7CB4E4BED5C33F619654321344" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Effective income tax rate reconciliation share-based compensation excess tax benefit amount </link:label>
<link:label id="lab_it_EffectiveIncomeTaxRateReconciliationShareBasedCompensationExcessTaxBenefitAmount_0AA25E7CB4E4BED5C33F619654321344_label_en-US" xlink:label="lab_it_EffectiveIncomeTaxRateReconciliationShareBasedCompensationExcessTaxBenefitAmount_0AA25E7CB4E4BED5C33F619654321344" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Effective Income Tax Rate Reconciliation Share Based Compensation Excess Tax Benefit Amount </link:label>
<link:label id="lab_it_EffectiveIncomeTaxRateReconciliationShareBasedCompensationExcessTaxBenefitAmount_0AA25E7CB4E4BED5C33F619654321344_documentation_en-US" xlink:label="lab_it_EffectiveIncomeTaxRateReconciliationShareBasedCompensationExcessTaxBenefitAmount_0AA25E7CB4E4BED5C33F619654321344" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US"> Effective Income Tax Rate Reconciliation Share Based Compensation Excess Tax Benefit Amount </link:label>
<link:loc xlink:href="it-20161231.xsd#it_EffectiveIncomeTaxRateReconciliationShareBasedCompensationExcessTaxBenefitAmount" xlink:label="loc_it_EffectiveIncomeTaxRateReconciliationShareBasedCompensationExcessTaxBenefitAmount_0AA25E7CB4E4BED5C33F619654321344" xlink:type="locator"/>
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<link:label id="lab_us-gaap_IncomeTaxReconciliationStateAndLocalIncomeTaxes_E23589C08813219FE539619659514EA6_terseLabel_en-US" xlink:label="lab_us-gaap_IncomeTaxReconciliationStateAndLocalIncomeTaxes_E23589C08813219FE539619659514EA6" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Effective income tax rate reconciliation, state and local income taxes, amount </link:label>
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<link:label id="lab_it_EarningsOfCertainNonUSSubsidiariesIndefinitelyReinvested_040875EE6D59B51BFCF96196543370EC_label_en-US" xlink:label="lab_it_EarningsOfCertainNonUSSubsidiariesIndefinitelyReinvested_040875EE6D59B51BFCF96196543370EC" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Earnings Of Certain Non US Subsidiaries Indefinitely Reinvested </link:label>
<link:label id="lab_it_EarningsOfCertainNonUSSubsidiariesIndefinitelyReinvested_040875EE6D59B51BFCF96196543370EC_documentation_en-US" xlink:label="lab_it_EarningsOfCertainNonUSSubsidiariesIndefinitelyReinvested_040875EE6D59B51BFCF96196543370EC" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US"> Earnings of Certain Non US Subsidiaries Indefinitely Reinvested </link:label>
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<link:label id="lab_us-gaap_DeferredTaxLiabilitiesUndistributedForeignEarnings_6DA1B555D46BF0622F1C6196543337E8_terseLabel_en-US" xlink:label="lab_us-gaap_DeferredTaxLiabilitiesUndistributedForeignEarnings_6DA1B555D46BF0622F1C6196543337E8" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Undistributed foreign earnings </link:label>
<link:label id="lab_us-gaap_DeferredTaxLiabilitiesUndistributedForeignEarnings_6DA1B555D46BF0622F1C6196543337E8_label_en-US" xlink:label="lab_us-gaap_DeferredTaxLiabilitiesUndistributedForeignEarnings_6DA1B555D46BF0622F1C6196543337E8" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Deferred Tax Liabilities, Undistributed Foreign Earnings </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_DeferredTaxLiabilitiesUndistributedForeignEarnings" xlink:label="loc_us-gaap_DeferredTaxLiabilitiesUndistributedForeignEarnings_6DA1B555D46BF0622F1C6196543337E8" xlink:type="locator"/>
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<link:label id="lab_us-gaap_OrganizationConsolidationBasisOfPresentationBusinessDescriptionAndAccountingPoliciesTextBlock_86A834AFDCCC03EAA896E53BFD891D55_terseLabel_en-US" xlink:label="lab_us-gaap_OrganizationConsolidationBasisOfPresentationBusinessDescriptionAndAccountingPoliciesTextBlock_86A834AFDCCC03EAA896E53BFD891D55" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> BUSINESS AND SIGNIFICANT ACCOUNTING POLICIES </link:label>
<link:label id="lab_us-gaap_OrganizationConsolidationBasisOfPresentationBusinessDescriptionAndAccountingPoliciesTextBlock_86A834AFDCCC03EAA896E53BFD891D55_label_en-US" xlink:label="lab_us-gaap_OrganizationConsolidationBasisOfPresentationBusinessDescriptionAndAccountingPoliciesTextBlock_86A834AFDCCC03EAA896E53BFD891D55" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Organization, Consolidation, Basis of Presentation, Business Description and Accounting Policies [Text Block] </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_OrganizationConsolidationBasisOfPresentationBusinessDescriptionAndAccountingPoliciesTextBlock" xlink:label="loc_us-gaap_OrganizationConsolidationBasisOfPresentationBusinessDescriptionAndAccountingPoliciesTextBlock_86A834AFDCCC03EAA896E53BFD891D55" xlink:type="locator"/>
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<link:label id="lab_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_D7DC02D0D4741FFB860C478A5AA8A8B7_terseLabel_en-US" xlink:label="lab_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_D7DC02D0D4741FFB860C478A5AA8A8B7" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Fair Value Measurements, Recurring and Nonrecurring [Table] </link:label>
<link:label id="lab_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_D7DC02D0D4741FFB860C478A5AA8A8B7_label_en-US" xlink:label="lab_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_D7DC02D0D4741FFB860C478A5AA8A8B7" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Fair Value Measurements, Recurring and Nonrecurring [Table] </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_D7DC02D0D4741FFB860C478A5AA8A8B7" xlink:type="locator"/>
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<link:label id="lab_us-gaap_FairValueByFairValueHierarchyLevelAxis_DE78B4B01BC8B731DBF5478A5AA88B38_terseLabel_en-US" xlink:label="lab_us-gaap_FairValueByFairValueHierarchyLevelAxis_DE78B4B01BC8B731DBF5478A5AA88B38" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Fair Value, Hierarchy [Axis] </link:label>
<link:label id="lab_us-gaap_FairValueByFairValueHierarchyLevelAxis_DE78B4B01BC8B731DBF5478A5AA88B38_label_en-US" xlink:label="lab_us-gaap_FairValueByFairValueHierarchyLevelAxis_DE78B4B01BC8B731DBF5478A5AA88B38" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Fair Value, Hierarchy [Axis] </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis" xlink:label="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_DE78B4B01BC8B731DBF5478A5AA88B38" xlink:type="locator"/>
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<link:label id="lab_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_0BEFD6E2FABFBBA5B059478A5AA949CA_terseLabel_en-US" xlink:label="lab_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_0BEFD6E2FABFBBA5B059478A5AA949CA" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Fair Value Hierarchy [Domain] </link:label>
<link:label id="lab_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_0BEFD6E2FABFBBA5B059478A5AA949CA_label_en-US" xlink:label="lab_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_0BEFD6E2FABFBBA5B059478A5AA949CA" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Fair Value Hierarchy [Domain] </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_0BEFD6E2FABFBBA5B059478A5AA949CA" xlink:type="locator"/>
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<link:label id="lab_us-gaap_FairValueInputsLevel1Member_5DB5847D57299F59B9F5478A5AA9CE2F_terseLabel_en-US" xlink:label="lab_us-gaap_FairValueInputsLevel1Member_5DB5847D57299F59B9F5478A5AA9CE2F" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Level 1 </link:label>
<link:label id="lab_us-gaap_FairValueInputsLevel1Member_5DB5847D57299F59B9F5478A5AA9CE2F_label_en-US" xlink:label="lab_us-gaap_FairValueInputsLevel1Member_5DB5847D57299F59B9F5478A5AA9CE2F" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Fair Value, Inputs, Level 1 [Member] </link:label>
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<link:label id="lab_us-gaap_FairValueInputsLevel2Member_BBE56F1A67FD317B5C81478A5AA99608_terseLabel_en-US" xlink:label="lab_us-gaap_FairValueInputsLevel2Member_BBE56F1A67FD317B5C81478A5AA99608" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Level 2 </link:label>
<link:label id="lab_us-gaap_FairValueInputsLevel2Member_BBE56F1A67FD317B5C81478A5AA99608_label_en-US" xlink:label="lab_us-gaap_FairValueInputsLevel2Member_BBE56F1A67FD317B5C81478A5AA99608" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Fair Value, Inputs, Level 2 [Member] </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_FairValueInputsLevel2Member" xlink:label="loc_us-gaap_FairValueInputsLevel2Member_BBE56F1A67FD317B5C81478A5AA99608" xlink:type="locator"/>
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<link:label id="lab_us-gaap_DerivativeInstrumentRiskAxis_14808B26E038EC05965B478A5AA90DB2_terseLabel_en-US" xlink:label="lab_us-gaap_DerivativeInstrumentRiskAxis_14808B26E038EC05965B478A5AA90DB2" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Derivative Instrument [Axis] </link:label>
<link:label id="lab_us-gaap_DerivativeInstrumentRiskAxis_14808B26E038EC05965B478A5AA90DB2_label_en-US" xlink:label="lab_us-gaap_DerivativeInstrumentRiskAxis_14808B26E038EC05965B478A5AA90DB2" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Derivative Instrument [Axis] </link:label>
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<link:label id="lab_us-gaap_DerivativeContractTypeDomain_FE44C601EA0CD615B9C0478A5AA9C75E_terseLabel_en-US" xlink:label="lab_us-gaap_DerivativeContractTypeDomain_FE44C601EA0CD615B9C0478A5AA9C75E" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Derivative Contract [Domain] </link:label>
<link:label id="lab_us-gaap_DerivativeContractTypeDomain_FE44C601EA0CD615B9C0478A5AA9C75E_label_en-US" xlink:label="lab_us-gaap_DerivativeContractTypeDomain_FE44C601EA0CD615B9C0478A5AA9C75E" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Derivative Contract [Domain] </link:label>
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<link:label id="lab_it_ForeignCurrencyForwardContractsNetMember_298CAD7CBC38C3EA88F8478A5AA99B01_terseLabel_en-US" xlink:label="lab_it_ForeignCurrencyForwardContractsNetMember_298CAD7CBC38C3EA88F8478A5AA99B01" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Foreign currency forward contracts </link:label>
<link:label id="lab_it_ForeignCurrencyForwardContractsNetMember_298CAD7CBC38C3EA88F8478A5AA99B01_label_en-US" xlink:label="lab_it_ForeignCurrencyForwardContractsNetMember_298CAD7CBC38C3EA88F8478A5AA99B01" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Foreign Currency Forward Contracts Net [Member] </link:label>
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<link:loc xlink:href="it-20161231.xsd#it_ForeignCurrencyForwardContractsNetMember" xlink:label="loc_it_ForeignCurrencyForwardContractsNetMember_298CAD7CBC38C3EA88F8478A5AA99B01" xlink:type="locator"/>
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<link:label id="lab_it_InterestRateSwapContractsMember_0DD6177FBB1CA81F263C478A5AAA3108_terseLabel_en-US" xlink:label="lab_it_InterestRateSwapContractsMember_0DD6177FBB1CA81F263C478A5AAA3108" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Interest rate swap contracts </link:label>
<link:label id="lab_it_InterestRateSwapContractsMember_0DD6177FBB1CA81F263C478A5AAA3108_label_en-US" xlink:label="lab_it_InterestRateSwapContractsMember_0DD6177FBB1CA81F263C478A5AAA3108" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Interest Rate Swap Contracts [Member] </link:label>
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<link:loc xlink:href="it-20161231.xsd#it_InterestRateSwapContractsMember" xlink:label="loc_it_InterestRateSwapContractsMember_0DD6177FBB1CA81F263C478A5AAA3108" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_it_InterestRateSwapContractsMember_0DD6177FBB1CA81F263C478A5AAA3108" xlink:to="lab_it_InterestRateSwapContractsMember_0DD6177FBB1CA81F263C478A5AAA3108" xlink:type="arc"/>
<link:label id="lab_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_0B2319975735043891BA478A5AAACFE3_terseLabel_en-US" xlink:label="lab_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_0B2319975735043891BA478A5AAACFE3" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] </link:label>
<link:label id="lab_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_0B2319975735043891BA478A5AAACFE3_label_en-US" xlink:label="lab_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_0B2319975735043891BA478A5AAACFE3" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_0B2319975735043891BA478A5AAACFE3" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_0B2319975735043891BA478A5AAACFE3" xlink:to="lab_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_0B2319975735043891BA478A5AAACFE3" xlink:type="arc"/>
<link:label id="lab_it_AssetsAbstract00_9815A17DA8564EB4665A478A5AAA9F42_terseLabel_en-US" xlink:label="lab_it_AssetsAbstract00_9815A17DA8564EB4665A478A5AAA9F42" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Assets: </link:label>
<link:label id="lab_it_AssetsAbstract00_9815A17DA8564EB4665A478A5AAA9F42_label_en-US" xlink:label="lab_it_AssetsAbstract00_9815A17DA8564EB4665A478A5AAA9F42" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Assets: [Abstract]0 </link:label>
<link:label id="lab_it_AssetsAbstract00_9815A17DA8564EB4665A478A5AAA9F42_documentation_en-US" xlink:label="lab_it_AssetsAbstract00_9815A17DA8564EB4665A478A5AAA9F42" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US"> -- None. No documentation exists for this element. -- </link:label>
<link:loc xlink:href="it-20161231.xsd#it_AssetsAbstract00" xlink:label="loc_it_AssetsAbstract00_9815A17DA8564EB4665A478A5AAA9F42" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_it_AssetsAbstract00_9815A17DA8564EB4665A478A5AAA9F42" xlink:to="lab_it_AssetsAbstract00_9815A17DA8564EB4665A478A5AAA9F42" xlink:type="arc"/>
<link:label id="lab_us-gaap_DeferredCompensationPlanAssets_58C4EF0D3039347E8BC1478A5AAC1E53_terseLabel_en-US" xlink:label="lab_us-gaap_DeferredCompensationPlanAssets_58C4EF0D3039347E8BC1478A5AAC1E53" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Deferred compensation plan assets </link:label>
<link:label id="lab_us-gaap_DeferredCompensationPlanAssets_58C4EF0D3039347E8BC1478A5AAC1E53_label_en-US" xlink:label="lab_us-gaap_DeferredCompensationPlanAssets_58C4EF0D3039347E8BC1478A5AAC1E53" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Deferred Compensation Plan Assets </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_DeferredCompensationPlanAssets" xlink:label="loc_us-gaap_DeferredCompensationPlanAssets_58C4EF0D3039347E8BC1478A5AAC1E53" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DeferredCompensationPlanAssets_58C4EF0D3039347E8BC1478A5AAC1E53" xlink:to="lab_us-gaap_DeferredCompensationPlanAssets_58C4EF0D3039347E8BC1478A5AAC1E53" xlink:type="arc"/>
<link:label id="lab_us-gaap_DerivativeAssets_DF719DB8C7EFCA3EF595478A5AAC25EE_terseLabel_en-US" xlink:label="lab_us-gaap_DerivativeAssets_DF719DB8C7EFCA3EF595478A5AAC25EE" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Derivative asset </link:label>
<link:label id="lab_us-gaap_DerivativeAssets_DF719DB8C7EFCA3EF595478A5AAC25EE_label_en-US" xlink:label="lab_us-gaap_DerivativeAssets_DF719DB8C7EFCA3EF595478A5AAC25EE" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Derivative Asset </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_DerivativeAssets" xlink:label="loc_us-gaap_DerivativeAssets_DF719DB8C7EFCA3EF595478A5AAC25EE" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DerivativeAssets_DF719DB8C7EFCA3EF595478A5AAC25EE" xlink:to="lab_us-gaap_DerivativeAssets_DF719DB8C7EFCA3EF595478A5AAC25EE" xlink:type="arc"/>
<link:label id="lab_us-gaap_AssetsFairValueDisclosure_C72EC796DC379B6D72AA478A5AACA56E_totalLabel_en-US" xlink:label="lab_us-gaap_AssetsFairValueDisclosure_C72EC796DC379B6D72AA478A5AACA56E" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:type="resource" xml:lang="en-US"> Assets measured at fair value on a recurring basis </link:label>
<link:label id="lab_us-gaap_AssetsFairValueDisclosure_C72EC796DC379B6D72AA478A5AACA56E_label_en-US" xlink:label="lab_us-gaap_AssetsFairValueDisclosure_C72EC796DC379B6D72AA478A5AACA56E" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Assets, Fair Value Disclosure </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_AssetsFairValueDisclosure" xlink:label="loc_us-gaap_AssetsFairValueDisclosure_C72EC796DC379B6D72AA478A5AACA56E" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_AssetsFairValueDisclosure_C72EC796DC379B6D72AA478A5AACA56E" xlink:to="lab_us-gaap_AssetsFairValueDisclosure_C72EC796DC379B6D72AA478A5AACA56E" xlink:type="arc"/>
<link:label id="lab_it_LiabilitiesAbstract0_419187794580636A16AC478A5AAC1909_terseLabel_en-US" xlink:label="lab_it_LiabilitiesAbstract0_419187794580636A16AC478A5AAC1909" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Liabilities: </link:label>
<link:label id="lab_it_LiabilitiesAbstract0_419187794580636A16AC478A5AAC1909_label_en-US" xlink:label="lab_it_LiabilitiesAbstract0_419187794580636A16AC478A5AAC1909" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Liabilities: [Abstract]0 </link:label>
<link:label id="lab_it_LiabilitiesAbstract0_419187794580636A16AC478A5AAC1909_documentation_en-US" xlink:label="lab_it_LiabilitiesAbstract0_419187794580636A16AC478A5AAC1909" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US"> -- None. No documentation exists for this element. -- </link:label>
<link:loc xlink:href="it-20161231.xsd#it_LiabilitiesAbstract0" xlink:label="loc_it_LiabilitiesAbstract0_419187794580636A16AC478A5AAC1909" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_it_LiabilitiesAbstract0_419187794580636A16AC478A5AAC1909" xlink:to="lab_it_LiabilitiesAbstract0_419187794580636A16AC478A5AAC1909" xlink:type="arc"/>
<link:label id="lab_us-gaap_DeferredCompensationLiabilityClassifiedNoncurrent_953E504F0A60B42298B4478A5AACBFF2_verboseLabel_en-US" xlink:label="lab_us-gaap_DeferredCompensationLiabilityClassifiedNoncurrent_953E504F0A60B42298B4478A5AACBFF2" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:type="resource" xml:lang="en-US"> Deferred compensation plan liabilities </link:label>
<link:label id="lab_us-gaap_DeferredCompensationLiabilityClassifiedNoncurrent_953E504F0A60B42298B4478A5AACBFF2_label_en-US" xlink:label="lab_us-gaap_DeferredCompensationLiabilityClassifiedNoncurrent_953E504F0A60B42298B4478A5AACBFF2" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Deferred Compensation Liability, Classified, Noncurrent </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_DeferredCompensationLiabilityClassifiedNoncurrent" xlink:label="loc_us-gaap_DeferredCompensationLiabilityClassifiedNoncurrent_953E504F0A60B42298B4478A5AACBFF2" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DeferredCompensationLiabilityClassifiedNoncurrent_953E504F0A60B42298B4478A5AACBFF2" xlink:to="lab_us-gaap_DeferredCompensationLiabilityClassifiedNoncurrent_953E504F0A60B42298B4478A5AACBFF2" xlink:type="arc"/>
<link:label id="lab_us-gaap_DerivativeLiabilities_0C87F045903D501DFFFD478A5AAC67CB_terseLabel_en-US" xlink:label="lab_us-gaap_DerivativeLiabilities_0C87F045903D501DFFFD478A5AAC67CB" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Derivative liability </link:label>
<link:label id="lab_us-gaap_DerivativeLiabilities_0C87F045903D501DFFFD478A5AAC67CB_label_en-US" xlink:label="lab_us-gaap_DerivativeLiabilities_0C87F045903D501DFFFD478A5AAC67CB" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Derivative Liability </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_DerivativeLiabilities" xlink:label="loc_us-gaap_DerivativeLiabilities_0C87F045903D501DFFFD478A5AAC67CB" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DerivativeLiabilities_0C87F045903D501DFFFD478A5AAC67CB" xlink:to="lab_us-gaap_DerivativeLiabilities_0C87F045903D501DFFFD478A5AAC67CB" xlink:type="arc"/>
<link:label id="lab_us-gaap_LiabilitiesFairValueDisclosure_E569DBA828DD0A383B40478A5AACC2D5_totalLabel_en-US" xlink:label="lab_us-gaap_LiabilitiesFairValueDisclosure_E569DBA828DD0A383B40478A5AACC2D5" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:type="resource" xml:lang="en-US"> Liabilities measured at fair value on a recurring basis </link:label>
<link:label id="lab_us-gaap_LiabilitiesFairValueDisclosure_E569DBA828DD0A383B40478A5AACC2D5_label_en-US" xlink:label="lab_us-gaap_LiabilitiesFairValueDisclosure_E569DBA828DD0A383B40478A5AACC2D5" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Financial and Nonfinancial Liabilities, Fair Value Disclosure </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_LiabilitiesFairValueDisclosure" xlink:label="loc_us-gaap_LiabilitiesFairValueDisclosure_E569DBA828DD0A383B40478A5AACC2D5" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_LiabilitiesFairValueDisclosure_E569DBA828DD0A383B40478A5AACC2D5" xlink:to="lab_us-gaap_LiabilitiesFairValueDisclosure_E569DBA828DD0A383B40478A5AACC2D5" xlink:type="arc"/>
<link:label id="lab_us-gaap_PensionAndOtherPostretirementBenefitsDisclosureTextBlock_F9282BC72F2FEF39D760E53BFDA8D5AA_terseLabel_en-US" xlink:label="lab_us-gaap_PensionAndOtherPostretirementBenefitsDisclosureTextBlock_F9282BC72F2FEF39D760E53BFDA8D5AA" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> EMPLOYEE BENEFITS </link:label>
<link:label id="lab_us-gaap_PensionAndOtherPostretirementBenefitsDisclosureTextBlock_F9282BC72F2FEF39D760E53BFDA8D5AA_label_en-US" xlink:label="lab_us-gaap_PensionAndOtherPostretirementBenefitsDisclosureTextBlock_F9282BC72F2FEF39D760E53BFDA8D5AA" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Pension and Other Postretirement Benefits Disclosure [Text Block] </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_PensionAndOtherPostretirementBenefitsDisclosureTextBlock" xlink:label="loc_us-gaap_PensionAndOtherPostretirementBenefitsDisclosureTextBlock_F9282BC72F2FEF39D760E53BFDA8D5AA" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_PensionAndOtherPostretirementBenefitsDisclosureTextBlock_F9282BC72F2FEF39D760E53BFDA8D5AA" xlink:to="lab_us-gaap_PensionAndOtherPostretirementBenefitsDisclosureTextBlock_F9282BC72F2FEF39D760E53BFDA8D5AA" xlink:type="arc"/>
<link:label id="lab_it_DeferredTaxAssetsAccruedExpenses_8A9B0FE11B3C79091FEA3E94362DD529_terseLabel_en-US" xlink:label="lab_it_DeferredTaxAssetsAccruedExpenses_8A9B0FE11B3C79091FEA3E94362DD529" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Accrued liabilities </link:label>
<link:label id="lab_it_DeferredTaxAssetsAccruedExpenses_8A9B0FE11B3C79091FEA3E94362DD529_label_en-US" xlink:label="lab_it_DeferredTaxAssetsAccruedExpenses_8A9B0FE11B3C79091FEA3E94362DD529" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Expense accruals </link:label>
<link:label id="lab_it_DeferredTaxAssetsAccruedExpenses_8A9B0FE11B3C79091FEA3E94362DD529_documentation_en-US" xlink:label="lab_it_DeferredTaxAssetsAccruedExpenses_8A9B0FE11B3C79091FEA3E94362DD529" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US"> Deferred tax assets accrued expenses </link:label>
<link:loc xlink:href="it-20161231.xsd#it_DeferredTaxAssetsAccruedExpenses" xlink:label="loc_it_DeferredTaxAssetsAccruedExpenses_8A9B0FE11B3C79091FEA3E94362DD529" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_it_DeferredTaxAssetsAccruedExpenses_8A9B0FE11B3C79091FEA3E94362DD529" xlink:to="lab_it_DeferredTaxAssetsAccruedExpenses_8A9B0FE11B3C79091FEA3E94362DD529" xlink:type="arc"/>
<link:label id="lab_it_DeferredTaxAssetsOperatingLossAndTaxCreditCarryforwards_30CCAF8D716879E367143E94362D1D0F_terseLabel_en-US" xlink:label="lab_it_DeferredTaxAssetsOperatingLossAndTaxCreditCarryforwards_30CCAF8D716879E367143E94362D1D0F" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Loss and credit carryforwards </link:label>
<link:label id="lab_it_DeferredTaxAssetsOperatingLossAndTaxCreditCarryforwards_30CCAF8D716879E367143E94362D1D0F_label_en-US" xlink:label="lab_it_DeferredTaxAssetsOperatingLossAndTaxCreditCarryforwards_30CCAF8D716879E367143E94362D1D0F" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Loss and credit carryforwards </link:label>
<link:label id="lab_it_DeferredTaxAssetsOperatingLossAndTaxCreditCarryforwards_30CCAF8D716879E367143E94362D1D0F_documentation_en-US" xlink:label="lab_it_DeferredTaxAssetsOperatingLossAndTaxCreditCarryforwards_30CCAF8D716879E367143E94362D1D0F" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US"> Deferred tax assets operating loss and tax credit carryforwards </link:label>
<link:loc xlink:href="it-20161231.xsd#it_DeferredTaxAssetsOperatingLossAndTaxCreditCarryforwards" xlink:label="loc_it_DeferredTaxAssetsOperatingLossAndTaxCreditCarryforwards_30CCAF8D716879E367143E94362D1D0F" xlink:type="locator"/>
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<link:label id="lab_us-gaap_DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsShareBasedCompensationCost_15540FBF11B8E330B8643E94362DDDF8_terseLabel_en-US" xlink:label="lab_us-gaap_DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsShareBasedCompensationCost_15540FBF11B8E330B8643E94362DDDF8" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Assets relating to equity compensation </link:label>
<link:label id="lab_us-gaap_DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsShareBasedCompensationCost_15540FBF11B8E330B8643E94362DDDF8_label_en-US" xlink:label="lab_us-gaap_DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsShareBasedCompensationCost_15540FBF11B8E330B8643E94362DDDF8" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Deferred Tax Assets, Tax Deferred Expense, Compensation and Benefits, Share-based Compensation Cost </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsShareBasedCompensationCost" xlink:label="loc_us-gaap_DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsShareBasedCompensationCost_15540FBF11B8E330B8643E94362DDDF8" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsShareBasedCompensationCost_15540FBF11B8E330B8643E94362DDDF8" xlink:to="lab_us-gaap_DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsShareBasedCompensationCost_15540FBF11B8E330B8643E94362DDDF8" xlink:type="arc"/>
<link:label id="lab_us-gaap_DeferredTaxAssetsOther_B1DC6C0B587B280838BD3E94362D453E_terseLabel_en-US" xlink:label="lab_us-gaap_DeferredTaxAssetsOther_B1DC6C0B587B280838BD3E94362D453E" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Other assets </link:label>
<link:label id="lab_us-gaap_DeferredTaxAssetsOther_B1DC6C0B587B280838BD3E94362D453E_label_en-US" xlink:label="lab_us-gaap_DeferredTaxAssetsOther_B1DC6C0B587B280838BD3E94362D453E" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Deferred Tax Assets, Other </link:label>
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<link:label id="lab_us-gaap_DeferredTaxAssetsGross_3F9A691A2EAEDA72AE043E94362D6BA0_label_en-US" xlink:label="lab_us-gaap_DeferredTaxAssetsGross_3F9A691A2EAEDA72AE043E94362D6BA0" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Deferred Tax Assets, Gross </link:label>
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<link:label id="lab_it_DeferredTaxLiabilitiesDepreciation_38215842E6AA8BB950D03E94362E2854_negatedLabel_en-US" xlink:label="lab_it_DeferredTaxLiabilitiesDepreciation_38215842E6AA8BB950D03E94362E2854" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:type="resource" xml:lang="en-US"> Property, equipment, and leasehold improvements </link:label>
<link:label id="lab_it_DeferredTaxLiabilitiesDepreciation_38215842E6AA8BB950D03E94362E2854_label_en-US" xlink:label="lab_it_DeferredTaxLiabilitiesDepreciation_38215842E6AA8BB950D03E94362E2854" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Deferred Tax Liabilities Depreciation </link:label>
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<link:loc xlink:href="it-20161231.xsd#it_DeferredTaxLiabilitiesDepreciation" xlink:label="loc_it_DeferredTaxLiabilitiesDepreciation_38215842E6AA8BB950D03E94362E2854" xlink:type="locator"/>
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<link:label id="lab_us-gaap_DeferredTaxLiabilitiesGoodwillAndIntangibleAssets_2724F57A29193928D94A3E94362E75DC_negatedLabel_en-US" xlink:label="lab_us-gaap_DeferredTaxLiabilitiesGoodwillAndIntangibleAssets_2724F57A29193928D94A3E94362E75DC" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:type="resource" xml:lang="en-US"> Intangible assets </link:label>
<link:label id="lab_us-gaap_DeferredTaxLiabilitiesGoodwillAndIntangibleAssets_2724F57A29193928D94A3E94362E75DC_label_en-US" xlink:label="lab_us-gaap_DeferredTaxLiabilitiesGoodwillAndIntangibleAssets_2724F57A29193928D94A3E94362E75DC" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Deferred Tax Liabilities, Goodwill and Intangible Assets </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_DeferredTaxLiabilitiesGoodwillAndIntangibleAssets" xlink:label="loc_us-gaap_DeferredTaxLiabilitiesGoodwillAndIntangibleAssets_2724F57A29193928D94A3E94362E75DC" xlink:type="locator"/>
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<link:label id="lab_us-gaap_DeferredTaxLiabilitiesPrepaidExpenses_DB42F6AECB556E2A55403E94362EC470_label_en-US" xlink:label="lab_us-gaap_DeferredTaxLiabilitiesPrepaidExpenses_DB42F6AECB556E2A55403E94362EC470" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Deferred Tax Liabilities, Prepaid Expenses </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_DeferredTaxLiabilitiesPrepaidExpenses" xlink:label="loc_us-gaap_DeferredTaxLiabilitiesPrepaidExpenses_DB42F6AECB556E2A55403E94362EC470" xlink:type="locator"/>
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<link:label id="lab_us-gaap_DeferredTaxLiabilitiesOther_5CEF6EE6BF77A45CB7AE3E94362E5872_negatedTerseLabel_en-US" xlink:label="lab_us-gaap_DeferredTaxLiabilitiesOther_5CEF6EE6BF77A45CB7AE3E94362E5872" xlink:role="http://www.xbrl.org/2009/role/negatedTerseLabel" xlink:type="resource" xml:lang="en-US"> Other liabilities </link:label>
<link:label id="lab_us-gaap_DeferredTaxLiabilitiesOther_5CEF6EE6BF77A45CB7AE3E94362E5872_label_en-US" xlink:label="lab_us-gaap_DeferredTaxLiabilitiesOther_5CEF6EE6BF77A45CB7AE3E94362E5872" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Deferred Tax Liabilities, Other </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_DeferredTaxLiabilitiesOther" xlink:label="loc_us-gaap_DeferredTaxLiabilitiesOther_5CEF6EE6BF77A45CB7AE3E94362E5872" xlink:type="locator"/>
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<link:label id="lab_us-gaap_DeferredIncomeTaxLiabilities_00FA371EA4281BB9EA953E94362E2683_negatedTotalLabel_en-US" xlink:label="lab_us-gaap_DeferredIncomeTaxLiabilities_00FA371EA4281BB9EA953E94362E2683" xlink:role="http://www.xbrl.org/2009/role/negatedTotalLabel" xlink:type="resource" xml:lang="en-US"> Gross deferred tax liabilities </link:label>
<link:label id="lab_us-gaap_DeferredIncomeTaxLiabilities_00FA371EA4281BB9EA953E94362E2683_label_en-US" xlink:label="lab_us-gaap_DeferredIncomeTaxLiabilities_00FA371EA4281BB9EA953E94362E2683" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Deferred Tax Liabilities, Gross </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_DeferredIncomeTaxLiabilities" xlink:label="loc_us-gaap_DeferredIncomeTaxLiabilities_00FA371EA4281BB9EA953E94362E2683" xlink:type="locator"/>
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<link:label id="lab_us-gaap_DeferredTaxAssetsValuationAllowance_B1486FA39A597896BBBD3E94362E8F70_negatedTerseLabel_en-US" xlink:label="lab_us-gaap_DeferredTaxAssetsValuationAllowance_B1486FA39A597896BBBD3E94362E8F70" xlink:role="http://www.xbrl.org/2009/role/negatedTerseLabel" xlink:type="resource" xml:lang="en-US"> Valuation allowance </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_DeferredTaxAssetsValuationAllowance" xlink:label="loc_us-gaap_DeferredTaxAssetsValuationAllowance_B1486FA39A597896BBBD3E94362E8F70" xlink:type="locator"/>
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<link:label id="lab_us-gaap_DeferredTaxAssetsLiabilitiesNet_86DFECA5DE9EBFE4BEF53E94362E391E_totalLabel_en-US" xlink:label="lab_us-gaap_DeferredTaxAssetsLiabilitiesNet_86DFECA5DE9EBFE4BEF53E94362E391E" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:type="resource" xml:lang="en-US"> Net deferred tax assets </link:label>
<link:label id="lab_us-gaap_DeferredTaxAssetsLiabilitiesNet_86DFECA5DE9EBFE4BEF53E94362E391E_label_en-US" xlink:label="lab_us-gaap_DeferredTaxAssetsLiabilitiesNet_86DFECA5DE9EBFE4BEF53E94362E391E" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Deferred Tax Assets, Net </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_DeferredTaxAssetsLiabilitiesNet" xlink:label="loc_us-gaap_DeferredTaxAssetsLiabilitiesNet_86DFECA5DE9EBFE4BEF53E94362E391E" xlink:type="locator"/>
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<link:label id="lab_us-gaap_DebtInstrumentTable_6A000618E26688E13EB54797E0F85118_terseLabel_en-US" xlink:label="lab_us-gaap_DebtInstrumentTable_6A000618E26688E13EB54797E0F85118" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Schedule of Long-term Debt Instruments [Table] </link:label>
<link:label id="lab_us-gaap_DebtInstrumentTable_6A000618E26688E13EB54797E0F85118_label_en-US" xlink:label="lab_us-gaap_DebtInstrumentTable_6A000618E26688E13EB54797E0F85118" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Schedule of Long-term Debt Instruments [Table] </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_DebtInstrumentTable" xlink:label="loc_us-gaap_DebtInstrumentTable_6A000618E26688E13EB54797E0F85118" xlink:type="locator"/>
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<link:label id="lab_us-gaap_LongtermDebtTypeAxis_410078FE2078A4C1EDE64797E0F9ABD6_terseLabel_en-US" xlink:label="lab_us-gaap_LongtermDebtTypeAxis_410078FE2078A4C1EDE64797E0F9ABD6" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Long-term Debt, Type [Axis] </link:label>
<link:label id="lab_us-gaap_LongtermDebtTypeAxis_410078FE2078A4C1EDE64797E0F9ABD6_label_en-US" xlink:label="lab_us-gaap_LongtermDebtTypeAxis_410078FE2078A4C1EDE64797E0F9ABD6" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Long-term Debt, Type [Axis] </link:label>
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<link:label id="lab_us-gaap_LongtermDebtTypeDomain_4BB481ACAB18595E9C734797E0F9301B_terseLabel_en-US" xlink:label="lab_us-gaap_LongtermDebtTypeDomain_4BB481ACAB18595E9C734797E0F9301B" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Long-term Debt, Type [Domain] </link:label>
<link:label id="lab_us-gaap_LongtermDebtTypeDomain_4BB481ACAB18595E9C734797E0F9301B_label_en-US" xlink:label="lab_us-gaap_LongtermDebtTypeDomain_4BB481ACAB18595E9C734797E0F9301B" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Long-term Debt, Type [Domain] </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_LongtermDebtTypeDomain" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_4BB481ACAB18595E9C734797E0F9301B" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_4BB481ACAB18595E9C734797E0F9301B" xlink:to="lab_us-gaap_LongtermDebtTypeDomain_4BB481ACAB18595E9C734797E0F9301B" xlink:type="arc"/>
<link:label id="lab_it_BankTermLoanMember_8CC7BE3E3288421F0D724797E0F95D36_terseLabel_en-US" xlink:label="lab_it_BankTermLoanMember_8CC7BE3E3288421F0D724797E0F95D36" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Term loan </link:label>
<link:label id="lab_it_BankTermLoanMember_8CC7BE3E3288421F0D724797E0F95D36_label_en-US" xlink:label="lab_it_BankTermLoanMember_8CC7BE3E3288421F0D724797E0F95D36" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Bank Term Loan [Member] </link:label>
<link:label id="lab_it_BankTermLoanMember_8CC7BE3E3288421F0D724797E0F95D36_documentation_en-US" xlink:label="lab_it_BankTermLoanMember_8CC7BE3E3288421F0D724797E0F95D36" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US"> -- None. No documentation exists for this element. -- </link:label>
<link:loc xlink:href="it-20161231.xsd#it_BankTermLoanMember" xlink:label="loc_it_BankTermLoanMember_8CC7BE3E3288421F0D724797E0F95D36" xlink:type="locator"/>
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<link:label id="lab_it_ConnecticutEconomicDevelopmentProgramMember_A5E75FA8F8F01326AFA54797E0F997D9_terseLabel_en-US" xlink:label="lab_it_ConnecticutEconomicDevelopmentProgramMember_A5E75FA8F8F01326AFA54797E0F997D9" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Connecticut Economic Development Program </link:label>
<link:label id="lab_it_ConnecticutEconomicDevelopmentProgramMember_A5E75FA8F8F01326AFA54797E0F997D9_label_en-US" xlink:label="lab_it_ConnecticutEconomicDevelopmentProgramMember_A5E75FA8F8F01326AFA54797E0F997D9" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Connecticut Economic Development Program [Member] </link:label>
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<link:loc xlink:href="it-20161231.xsd#it_ConnecticutEconomicDevelopmentProgramMember" xlink:label="loc_it_ConnecticutEconomicDevelopmentProgramMember_A5E75FA8F8F01326AFA54797E0F997D9" xlink:type="locator"/>
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<link:label id="lab_us-gaap_RevolvingCreditFacilityMember_F8B52EABB891F1EF585E4797E0F90146_terseLabel_en-US" xlink:label="lab_us-gaap_RevolvingCreditFacilityMember_F8B52EABB891F1EF585E4797E0F90146" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Revolving Credit Facility </link:label>
<link:label id="lab_us-gaap_RevolvingCreditFacilityMember_F8B52EABB891F1EF585E4797E0F90146_label_en-US" xlink:label="lab_us-gaap_RevolvingCreditFacilityMember_F8B52EABB891F1EF585E4797E0F90146" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Revolving Credit Facility [Member] </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_RevolvingCreditFacilityMember" xlink:label="loc_us-gaap_RevolvingCreditFacilityMember_F8B52EABB891F1EF585E4797E0F90146" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_RevolvingCreditFacilityMember_F8B52EABB891F1EF585E4797E0F90146" xlink:to="lab_us-gaap_RevolvingCreditFacilityMember_F8B52EABB891F1EF585E4797E0F90146" xlink:type="arc"/>
<link:label id="lab_us-gaap_DebtInstrumentLineItems_A12842C6B1149B834D924797E0F9D3CF_terseLabel_en-US" xlink:label="lab_us-gaap_DebtInstrumentLineItems_A12842C6B1149B834D924797E0F9D3CF" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Debt Instrument [Line Items] </link:label>
<link:label id="lab_us-gaap_DebtInstrumentLineItems_A12842C6B1149B834D924797E0F9D3CF_label_en-US" xlink:label="lab_us-gaap_DebtInstrumentLineItems_A12842C6B1149B834D924797E0F9D3CF" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Debt Instrument [Line Items] </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_DebtInstrumentLineItems" xlink:label="loc_us-gaap_DebtInstrumentLineItems_A12842C6B1149B834D924797E0F9D3CF" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DebtInstrumentLineItems_A12842C6B1149B834D924797E0F9D3CF" xlink:to="lab_us-gaap_DebtInstrumentLineItems_A12842C6B1149B834D924797E0F9D3CF" xlink:type="arc"/>
<link:label id="lab_us-gaap_DebtInstrumentCarryingAmount_9714C0F30EAFBBA7B5614797E0F9D70F_terseLabel_en-US" xlink:label="lab_us-gaap_DebtInstrumentCarryingAmount_9714C0F30EAFBBA7B5614797E0F9D70F" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Long-term debt, gross </link:label>
<link:label id="lab_us-gaap_DebtInstrumentCarryingAmount_9714C0F30EAFBBA7B5614797E0F9D70F_label_en-US" xlink:label="lab_us-gaap_DebtInstrumentCarryingAmount_9714C0F30EAFBBA7B5614797E0F9D70F" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Long-term Debt, Gross </link:label>
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<link:label id="lab_us-gaap_DebtIssuanceCostsLineOfCreditArrangementsNet_BCD0F2FB662CFDDC6FAC4797E0F997C7_negatedTerseLabel_en-US" xlink:label="lab_us-gaap_DebtIssuanceCostsLineOfCreditArrangementsNet_BCD0F2FB662CFDDC6FAC4797E0F997C7" xlink:role="http://www.xbrl.org/2009/role/negatedTerseLabel" xlink:type="resource" xml:lang="en-US"> Less: deferred financing fees </link:label>
<link:label id="lab_us-gaap_DebtIssuanceCostsLineOfCreditArrangementsNet_BCD0F2FB662CFDDC6FAC4797E0F997C7_label_en-US" xlink:label="lab_us-gaap_DebtIssuanceCostsLineOfCreditArrangementsNet_BCD0F2FB662CFDDC6FAC4797E0F997C7" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Debt Issuance Costs, Line of Credit Arrangements, Net </link:label>
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<link:label id="lab_us-gaap_LongTermDebt_55413C18F703897127674797E0F98167_totalLabel_en-US" xlink:label="lab_us-gaap_LongTermDebt_55413C18F703897127674797E0F98167" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:type="resource" xml:lang="en-US"> Long-term debt </link:label>
<link:label id="lab_us-gaap_LongTermDebt_55413C18F703897127674797E0F98167_label_en-US" xlink:label="lab_us-gaap_LongTermDebt_55413C18F703897127674797E0F98167" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Long-term Debt </link:label>
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<link:label id="lab_us-gaap_RestrictedStockUnitsRSUMember_FAB58999FE0594691B4DB3594A5DC756_terseLabel_en-US" xlink:label="lab_us-gaap_RestrictedStockUnitsRSUMember_FAB58999FE0594691B4DB3594A5DC756" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Restricted Stock Units (RSUs) </link:label>
<link:label id="lab_us-gaap_RestrictedStockUnitsRSUMember_FAB58999FE0594691B4DB3594A5DC756_label_en-US" xlink:label="lab_us-gaap_RestrictedStockUnitsRSUMember_FAB58999FE0594691B4DB3594A5DC756" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Restricted Stock Units (RSUs) [Member] </link:label>
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<link:label id="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_46E558552DF7E2403CB5B3594A5D4F55_verboseLabel_en-US" xlink:label="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_46E558552DF7E2403CB5B3594A5D4F55" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:type="resource" xml:lang="en-US"> Restricted Stock Units (RSUs) </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedRollForward_46E558552DF7E2403CB5B3594A5D4F55" xlink:type="locator"/>
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<link:label id="lab_it_SharebasedCompensationArrangementBySharebasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedAndReleasedInPeriod_6B91C206E09CF6847860B3594A5D3EC9_negatedTerseLabel_en-US" xlink:label="lab_it_SharebasedCompensationArrangementBySharebasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedAndReleasedInPeriod_6B91C206E09CF6847860B3594A5D3EC9" xlink:role="http://www.xbrl.org/2009/role/negatedTerseLabel" xlink:type="resource" xml:lang="en-US"> Vested and released (in shares) </link:label>
<link:label id="lab_it_SharebasedCompensationArrangementBySharebasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedAndReleasedInPeriod_6B91C206E09CF6847860B3594A5D3EC9_label_en-US" xlink:label="lab_it_SharebasedCompensationArrangementBySharebasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedAndReleasedInPeriod_6B91C206E09CF6847860B3594A5D3EC9" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Vested and released </link:label>
<link:label id="lab_it_SharebasedCompensationArrangementBySharebasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedAndReleasedInPeriod_6B91C206E09CF6847860B3594A5D3EC9_documentation_en-US" xlink:label="lab_it_SharebasedCompensationArrangementBySharebasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedAndReleasedInPeriod_6B91C206E09CF6847860B3594A5D3EC9" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US"> Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested and Released in Period. </link:label>
<link:loc xlink:href="it-20161231.xsd#it_SharebasedCompensationArrangementBySharebasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedAndReleasedInPeriod" xlink:label="loc_it_SharebasedCompensationArrangementBySharebasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedAndReleasedInPeriod_6B91C206E09CF6847860B3594A5D3EC9" xlink:type="locator"/>
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<link:label id="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_84945C5FE55BAA04DF77B3594A5DF9BE_verboseLabel_en-US" xlink:label="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_84945C5FE55BAA04DF77B3594A5DF9BE" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:type="resource" xml:lang="en-US"> Per Share Weighted Average Grant Date Fair Value </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_84945C5FE55BAA04DF77B3594A5DF9BE" xlink:type="locator"/>
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<link:label id="lab_it_SharebasedCompensationArrangementBySharebasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedAndReleasedInPeriodWeightedAverageGrantDateFairValue_50E5317149E844F16955B3594A5EC355_terseLabel_en-US" xlink:label="lab_it_SharebasedCompensationArrangementBySharebasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedAndReleasedInPeriodWeightedAverageGrantDateFairValue_50E5317149E844F16955B3594A5EC355" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Vested and released (in Dollars per share) </link:label>
<link:label id="lab_it_SharebasedCompensationArrangementBySharebasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedAndReleasedInPeriodWeightedAverageGrantDateFairValue_50E5317149E844F16955B3594A5EC355_label_en-US" xlink:label="lab_it_SharebasedCompensationArrangementBySharebasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedAndReleasedInPeriodWeightedAverageGrantDateFairValue_50E5317149E844F16955B3594A5EC355" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Vested and released (in Dollars per share) </link:label>
<link:label id="lab_it_SharebasedCompensationArrangementBySharebasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedAndReleasedInPeriodWeightedAverageGrantDateFairValue_50E5317149E844F16955B3594A5EC355_documentation_en-US" xlink:label="lab_it_SharebasedCompensationArrangementBySharebasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedAndReleasedInPeriodWeightedAverageGrantDateFairValue_50E5317149E844F16955B3594A5EC355" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US"> Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other Than Options Vested And Released In Period Weighted Average Grant Date Fair Value. </link:label>
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<link:label id="lab_us-gaap_ScheduleOfAccountsPayableAndAccruedLiabilitiesTableTextBlock_10698F07CA7A744B112FE53BFB915C8B_terseLabel_en-US" xlink:label="lab_us-gaap_ScheduleOfAccountsPayableAndAccruedLiabilitiesTableTextBlock_10698F07CA7A744B112FE53BFB915C8B" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Schedule of Accounts Payable and Accrued Liabilities </link:label>
<link:label id="lab_us-gaap_ScheduleOfAccountsPayableAndAccruedLiabilitiesTableTextBlock_10698F07CA7A744B112FE53BFB915C8B_label_en-US" xlink:label="lab_us-gaap_ScheduleOfAccountsPayableAndAccruedLiabilitiesTableTextBlock_10698F07CA7A744B112FE53BFB915C8B" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Schedule of Accounts Payable and Accrued Liabilities [Table Text Block] </link:label>
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<link:label id="lab_us-gaap_ScheduleOfOtherAssetsAndOtherLiabilitiesTableTextBlock_CC4E7894CA1EC55D409AE53BFB916D14_terseLabel_en-US" xlink:label="lab_us-gaap_ScheduleOfOtherAssetsAndOtherLiabilitiesTableTextBlock_CC4E7894CA1EC55D409AE53BFB916D14" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Schedule of Other Liabilities </link:label>
<link:label id="lab_us-gaap_ScheduleOfOtherAssetsAndOtherLiabilitiesTableTextBlock_CC4E7894CA1EC55D409AE53BFB916D14_label_en-US" xlink:label="lab_us-gaap_ScheduleOfOtherAssetsAndOtherLiabilitiesTableTextBlock_CC4E7894CA1EC55D409AE53BFB916D14" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Schedule of Other Assets and Other Liabilities [Table Text Block] </link:label>
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<link:label id="lab_us-gaap_DeferredRevenueNoncurrent_174DACC62B221C0024E03ED1D699FFBC_terseLabel_en-US" xlink:label="lab_us-gaap_DeferredRevenueNoncurrent_174DACC62B221C0024E03ED1D699FFBC" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Non-current deferred revenue </link:label>
<link:label id="lab_us-gaap_DeferredRevenueNoncurrent_174DACC62B221C0024E03ED1D699FFBC_label_en-US" xlink:label="lab_us-gaap_DeferredRevenueNoncurrent_174DACC62B221C0024E03ED1D699FFBC" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Deferred Revenue, Noncurrent </link:label>
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<link:label id="lab_it_TaxesPayableNoncurrent_F645B7910B05EB573D823ED1D6995A9A_terseLabel_en-US" xlink:label="lab_it_TaxesPayableNoncurrent_F645B7910B05EB573D823ED1D6995A9A" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Long-term taxes payable </link:label>
<link:label id="lab_it_TaxesPayableNoncurrent_F645B7910B05EB573D823ED1D6995A9A_label_en-US" xlink:label="lab_it_TaxesPayableNoncurrent_F645B7910B05EB573D823ED1D6995A9A" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Long-term taxes payable </link:label>
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<link:label id="lab_us-gaap_DeferredRentCreditNoncurrent_AB74681C16F25390D2B43ED1D6996A82_terseLabel_en-US" xlink:label="lab_us-gaap_DeferredRentCreditNoncurrent_AB74681C16F25390D2B43ED1D6996A82" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Deferred rent </link:label>
<link:label id="lab_us-gaap_DeferredRentCreditNoncurrent_AB74681C16F25390D2B43ED1D6996A82_label_en-US" xlink:label="lab_us-gaap_DeferredRentCreditNoncurrent_AB74681C16F25390D2B43ED1D6996A82" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Deferred Rent Credit, Noncurrent </link:label>
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<link:label id="lab_us-gaap_DefinedBenefitPensionPlanLiabilitiesNoncurrent_8CE7F82FD4A963E7E17A3ED1D699B639_terseLabel_en-US" xlink:label="lab_us-gaap_DefinedBenefitPensionPlanLiabilitiesNoncurrent_8CE7F82FD4A963E7E17A3ED1D699B639" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Benefit plan-related liabilities </link:label>
<link:label id="lab_us-gaap_DefinedBenefitPensionPlanLiabilitiesNoncurrent_8CE7F82FD4A963E7E17A3ED1D699B639_label_en-US" xlink:label="lab_us-gaap_DefinedBenefitPensionPlanLiabilitiesNoncurrent_8CE7F82FD4A963E7E17A3ED1D699B639" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Defined Benefit Pension Plan, Liabilities, Noncurrent </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_DefinedBenefitPensionPlanLiabilitiesNoncurrent" xlink:label="loc_us-gaap_DefinedBenefitPensionPlanLiabilitiesNoncurrent_8CE7F82FD4A963E7E17A3ED1D699B639" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DefinedBenefitPensionPlanLiabilitiesNoncurrent_8CE7F82FD4A963E7E17A3ED1D699B639" xlink:to="lab_us-gaap_DefinedBenefitPensionPlanLiabilitiesNoncurrent_8CE7F82FD4A963E7E17A3ED1D699B639" xlink:type="arc"/>
<link:label id="lab_it_OtherLiabilitiesNoncurrentOther_C46AD5BFC364EFC855913ED1D6998BED_terseLabel_en-US" xlink:label="lab_it_OtherLiabilitiesNoncurrentOther_C46AD5BFC364EFC855913ED1D6998BED" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Other </link:label>
<link:label id="lab_it_OtherLiabilitiesNoncurrentOther_C46AD5BFC364EFC855913ED1D6998BED_label_en-US" xlink:label="lab_it_OtherLiabilitiesNoncurrentOther_C46AD5BFC364EFC855913ED1D6998BED" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Other Liabilities Noncurrent Other </link:label>
<link:label id="lab_it_OtherLiabilitiesNoncurrentOther_C46AD5BFC364EFC855913ED1D6998BED_documentation_en-US" xlink:label="lab_it_OtherLiabilitiesNoncurrentOther_C46AD5BFC364EFC855913ED1D6998BED" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US"> Other liabilities noncurrent other </link:label>
<link:loc xlink:href="it-20161231.xsd#it_OtherLiabilitiesNoncurrentOther" xlink:label="loc_it_OtherLiabilitiesNoncurrentOther_C46AD5BFC364EFC855913ED1D6998BED" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_it_OtherLiabilitiesNoncurrentOther_C46AD5BFC364EFC855913ED1D6998BED" xlink:to="lab_it_OtherLiabilitiesNoncurrentOther_C46AD5BFC364EFC855913ED1D6998BED" xlink:type="arc"/>
<link:label id="lab_us-gaap_OtherLiabilitiesNoncurrent_7B73840BD6294E9185323ED1D699F26C_totalLabel_en-US" xlink:label="lab_us-gaap_OtherLiabilitiesNoncurrent_7B73840BD6294E9185323ED1D699F26C" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:type="resource" xml:lang="en-US"> Total other liabilities </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_OtherLiabilitiesNoncurrent" xlink:label="loc_us-gaap_OtherLiabilitiesNoncurrent_7B73840BD6294E9185323ED1D699F26C" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_OtherLiabilitiesNoncurrent_7B73840BD6294E9185323ED1D699F26C" xlink:to="lab_us-gaap_OtherLiabilitiesNoncurrent_7B73840BD6294E9185323ED1D699F26C" xlink:type="arc"/>
<link:label id="lab_it_AccountingStandardsUpdate201609StatutoryTaxWithholdingComponentMember_C6B2E7190B5D1131D02C3FEE57A6042F_terseLabel_en-US" xlink:label="lab_it_AccountingStandardsUpdate201609StatutoryTaxWithholdingComponentMember_C6B2E7190B5D1131D02C3FEE57A6042F" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Accounting Standards Update 2016-09, Statutory Tax Withholding Component </link:label>
<link:label id="lab_it_AccountingStandardsUpdate201609StatutoryTaxWithholdingComponentMember_C6B2E7190B5D1131D02C3FEE57A6042F_label_en-US" xlink:label="lab_it_AccountingStandardsUpdate201609StatutoryTaxWithholdingComponentMember_C6B2E7190B5D1131D02C3FEE57A6042F" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Accounting Standards Update 2016-09, Statutory Tax Withholding Component [Member] </link:label>
<link:label id="lab_it_AccountingStandardsUpdate201609StatutoryTaxWithholdingComponentMember_C6B2E7190B5D1131D02C3FEE57A6042F_documentation_en-US" xlink:label="lab_it_AccountingStandardsUpdate201609StatutoryTaxWithholdingComponentMember_C6B2E7190B5D1131D02C3FEE57A6042F" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US"> Accounting Standards Update 2016-09, Statutory Tax Withholding Component [Member] </link:label>
<link:loc xlink:href="it-20161231.xsd#it_AccountingStandardsUpdate201609StatutoryTaxWithholdingComponentMember" xlink:label="loc_it_AccountingStandardsUpdate201609StatutoryTaxWithholdingComponentMember_C6B2E7190B5D1131D02C3FEE57A6042F" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_it_AccountingStandardsUpdate201609StatutoryTaxWithholdingComponentMember_C6B2E7190B5D1131D02C3FEE57A6042F" xlink:to="lab_it_AccountingStandardsUpdate201609StatutoryTaxWithholdingComponentMember_C6B2E7190B5D1131D02C3FEE57A6042F" xlink:type="arc"/>
<link:label id="lab_us-gaap_PerformanceSharesMember_9557133F4E0D306676643FEE57AEDF9A_terseLabel_en-US" xlink:label="lab_us-gaap_PerformanceSharesMember_9557133F4E0D306676643FEE57AEDF9A" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Performance Shares </link:label>
<link:label id="lab_us-gaap_PerformanceSharesMember_9557133F4E0D306676643FEE57AEDF9A_label_en-US" xlink:label="lab_us-gaap_PerformanceSharesMember_9557133F4E0D306676643FEE57AEDF9A" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Performance Shares [Member] </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_PerformanceSharesMember" xlink:label="loc_us-gaap_PerformanceSharesMember_9557133F4E0D306676643FEE57AEDF9A" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_PerformanceSharesMember_9557133F4E0D306676643FEE57AEDF9A" xlink:to="lab_us-gaap_PerformanceSharesMember_9557133F4E0D306676643FEE57AEDF9A" xlink:type="arc"/>
<link:label id="lab_it_RetirementEligibleEmployeesEquityAwardMember_89DAE11A4FF2060228A13FEE57AED7BB_terseLabel_en-US" xlink:label="lab_it_RetirementEligibleEmployeesEquityAwardMember_89DAE11A4FF2060228A13FEE57AED7BB" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Retirement Eligible Employees Equity Award </link:label>
<link:label id="lab_it_RetirementEligibleEmployeesEquityAwardMember_89DAE11A4FF2060228A13FEE57AED7BB_label_en-US" xlink:label="lab_it_RetirementEligibleEmployeesEquityAwardMember_89DAE11A4FF2060228A13FEE57AED7BB" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Retirement Eligible Employees Equity Award [Member] </link:label>
<link:label id="lab_it_RetirementEligibleEmployeesEquityAwardMember_89DAE11A4FF2060228A13FEE57AED7BB_documentation_en-US" xlink:label="lab_it_RetirementEligibleEmployeesEquityAwardMember_89DAE11A4FF2060228A13FEE57AED7BB" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US"> -- None. No documentation exists for this element. -- </link:label>
<link:loc xlink:href="it-20161231.xsd#it_RetirementEligibleEmployeesEquityAwardMember" xlink:label="loc_it_RetirementEligibleEmployeesEquityAwardMember_89DAE11A4FF2060228A13FEE57AED7BB" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_it_RetirementEligibleEmployeesEquityAwardMember_89DAE11A4FF2060228A13FEE57AED7BB" xlink:to="lab_it_RetirementEligibleEmployeesEquityAwardMember_89DAE11A4FF2060228A13FEE57AED7BB" xlink:type="arc"/>
<link:label id="lab_it_EmployeeStockPurchasePlanMember_82C1CAA0C1D1592EBE0E3FEE57AED1D1_terseLabel_en-US" xlink:label="lab_it_EmployeeStockPurchasePlanMember_82C1CAA0C1D1592EBE0E3FEE57AED1D1" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Employee Stock Purchase Plan </link:label>
<link:label id="lab_it_EmployeeStockPurchasePlanMember_82C1CAA0C1D1592EBE0E3FEE57AED1D1_label_en-US" xlink:label="lab_it_EmployeeStockPurchasePlanMember_82C1CAA0C1D1592EBE0E3FEE57AED1D1" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Employee Stock Purchase Plan [Member] </link:label>
<link:label id="lab_it_EmployeeStockPurchasePlanMember_82C1CAA0C1D1592EBE0E3FEE57AED1D1_documentation_en-US" xlink:label="lab_it_EmployeeStockPurchasePlanMember_82C1CAA0C1D1592EBE0E3FEE57AED1D1" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US"> -- None. No documentation exists for this element. -- </link:label>
<link:loc xlink:href="it-20161231.xsd#it_EmployeeStockPurchasePlanMember" xlink:label="loc_it_EmployeeStockPurchasePlanMember_82C1CAA0C1D1592EBE0E3FEE57AED1D1" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_it_EmployeeStockPurchasePlanMember_82C1CAA0C1D1592EBE0E3FEE57AED1D1" xlink:to="lab_it_EmployeeStockPurchasePlanMember_82C1CAA0C1D1592EBE0E3FEE57AED1D1" xlink:type="arc"/>
<link:label id="lab_us-gaap_TitleOfIndividualAxis_914E2ABAB2D85FB6EC233FEE57AEC674_terseLabel_en-US" xlink:label="lab_us-gaap_TitleOfIndividualAxis_914E2ABAB2D85FB6EC233FEE57AEC674" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Title of Individual [Axis] </link:label>
<link:label id="lab_us-gaap_TitleOfIndividualAxis_914E2ABAB2D85FB6EC233FEE57AEC674_label_en-US" xlink:label="lab_us-gaap_TitleOfIndividualAxis_914E2ABAB2D85FB6EC233FEE57AEC674" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Title of Individual [Axis] </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_TitleOfIndividualAxis" xlink:label="loc_us-gaap_TitleOfIndividualAxis_914E2ABAB2D85FB6EC233FEE57AEC674" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_TitleOfIndividualAxis_914E2ABAB2D85FB6EC233FEE57AEC674" xlink:to="lab_us-gaap_TitleOfIndividualAxis_914E2ABAB2D85FB6EC233FEE57AEC674" xlink:type="arc"/>
<link:label id="lab_us-gaap_TitleOfIndividualWithRelationshipToEntityDomain_7E1B0BD203B1C21DDCC83FEE57AE2014_terseLabel_en-US" xlink:label="lab_us-gaap_TitleOfIndividualWithRelationshipToEntityDomain_7E1B0BD203B1C21DDCC83FEE57AE2014" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Title of Individual with Relationship to Entity [Domain] </link:label>
<link:label id="lab_us-gaap_TitleOfIndividualWithRelationshipToEntityDomain_7E1B0BD203B1C21DDCC83FEE57AE2014_label_en-US" xlink:label="lab_us-gaap_TitleOfIndividualWithRelationshipToEntityDomain_7E1B0BD203B1C21DDCC83FEE57AE2014" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Relationship to Entity [Domain] </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_TitleOfIndividualWithRelationshipToEntityDomain" xlink:label="loc_us-gaap_TitleOfIndividualWithRelationshipToEntityDomain_7E1B0BD203B1C21DDCC83FEE57AE2014" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_TitleOfIndividualWithRelationshipToEntityDomain_7E1B0BD203B1C21DDCC83FEE57AE2014" xlink:to="lab_us-gaap_TitleOfIndividualWithRelationshipToEntityDomain_7E1B0BD203B1C21DDCC83FEE57AE2014" xlink:type="arc"/>
<link:label id="lab_us-gaap_ExecutiveOfficerMember_2CFACC3FFF555EC376073FEE57AE262F_terseLabel_en-US" xlink:label="lab_us-gaap_ExecutiveOfficerMember_2CFACC3FFF555EC376073FEE57AE262F" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Executive Officer </link:label>
<link:label id="lab_us-gaap_ExecutiveOfficerMember_2CFACC3FFF555EC376073FEE57AE262F_label_en-US" xlink:label="lab_us-gaap_ExecutiveOfficerMember_2CFACC3FFF555EC376073FEE57AE262F" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Executive Officer [Member] </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ExecutiveOfficerMember" xlink:label="loc_us-gaap_ExecutiveOfficerMember_2CFACC3FFF555EC376073FEE57AE262F" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ExecutiveOfficerMember_2CFACC3FFF555EC376073FEE57AE262F" xlink:to="lab_us-gaap_ExecutiveOfficerMember_2CFACC3FFF555EC376073FEE57AE262F" xlink:type="arc"/>
<link:label id="lab_it_NonExecutiveMember_AF7FB939E7E7F83CB0473FEE57AE1ED2_terseLabel_en-US" xlink:label="lab_it_NonExecutiveMember_AF7FB939E7E7F83CB0473FEE57AE1ED2" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Non Executive </link:label>
<link:label id="lab_it_NonExecutiveMember_AF7FB939E7E7F83CB0473FEE57AE1ED2_label_en-US" xlink:label="lab_it_NonExecutiveMember_AF7FB939E7E7F83CB0473FEE57AE1ED2" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Non Executive [Member] </link:label>
<link:label id="lab_it_NonExecutiveMember_AF7FB939E7E7F83CB0473FEE57AE1ED2_documentation_en-US" xlink:label="lab_it_NonExecutiveMember_AF7FB939E7E7F83CB0473FEE57AE1ED2" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US"> -- None. No documentation exists for this element. -- </link:label>
<link:loc xlink:href="it-20161231.xsd#it_NonExecutiveMember" xlink:label="loc_it_NonExecutiveMember_AF7FB939E7E7F83CB0473FEE57AE1ED2" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_it_NonExecutiveMember_AF7FB939E7E7F83CB0473FEE57AE1ED2" xlink:to="lab_it_NonExecutiveMember_AF7FB939E7E7F83CB0473FEE57AE1ED2" xlink:type="arc"/>
<link:label id="lab_it_RestrictedEquityAwardTypeAxis_F4E8466FC9513485161D3FEE57AEF98B_terseLabel_en-US" xlink:label="lab_it_RestrictedEquityAwardTypeAxis_F4E8466FC9513485161D3FEE57AEF98B" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Restricted Equity Award Type [Axis] </link:label>
<link:label id="lab_it_RestrictedEquityAwardTypeAxis_F4E8466FC9513485161D3FEE57AEF98B_label_en-US" xlink:label="lab_it_RestrictedEquityAwardTypeAxis_F4E8466FC9513485161D3FEE57AEF98B" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Restricted Equity Award Type [Axis] </link:label>
<link:label id="lab_it_RestrictedEquityAwardTypeAxis_F4E8466FC9513485161D3FEE57AEF98B_documentation_en-US" xlink:label="lab_it_RestrictedEquityAwardTypeAxis_F4E8466FC9513485161D3FEE57AEF98B" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US"> -- None. No documentation exists for this element. -- </link:label>
<link:loc xlink:href="it-20161231.xsd#it_RestrictedEquityAwardTypeAxis" xlink:label="loc_it_RestrictedEquityAwardTypeAxis_F4E8466FC9513485161D3FEE57AEF98B" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_it_RestrictedEquityAwardTypeAxis_F4E8466FC9513485161D3FEE57AEF98B" xlink:to="lab_it_RestrictedEquityAwardTypeAxis_F4E8466FC9513485161D3FEE57AEF98B" xlink:type="arc"/>
<link:label id="lab_it_RestrictedEquityAwardTypeDomain_13FF974554D3970873AF3FEE57AE3EE5_terseLabel_en-US" xlink:label="lab_it_RestrictedEquityAwardTypeDomain_13FF974554D3970873AF3FEE57AE3EE5" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> RestrictedEquityAwardType [Domain] </link:label>
<link:label id="lab_it_RestrictedEquityAwardTypeDomain_13FF974554D3970873AF3FEE57AE3EE5_label_en-US" xlink:label="lab_it_RestrictedEquityAwardTypeDomain_13FF974554D3970873AF3FEE57AE3EE5" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> RestrictedEquityAwardType [Domain] </link:label>
<link:label id="lab_it_RestrictedEquityAwardTypeDomain_13FF974554D3970873AF3FEE57AE3EE5_documentation_en-US" xlink:label="lab_it_RestrictedEquityAwardTypeDomain_13FF974554D3970873AF3FEE57AE3EE5" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US"> -- None. No documentation exists for this element. -- </link:label>
<link:loc xlink:href="it-20161231.xsd#it_RestrictedEquityAwardTypeDomain" xlink:label="loc_it_RestrictedEquityAwardTypeDomain_13FF974554D3970873AF3FEE57AE3EE5" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_it_RestrictedEquityAwardTypeDomain_13FF974554D3970873AF3FEE57AE3EE5" xlink:to="lab_it_RestrictedEquityAwardTypeDomain_13FF974554D3970873AF3FEE57AE3EE5" xlink:type="arc"/>
<link:label id="lab_it_ServiceBasedAwardsMember_93082FEDEFD9DE8054443FEE57AE7AEA_terseLabel_en-US" xlink:label="lab_it_ServiceBasedAwardsMember_93082FEDEFD9DE8054443FEE57AE7AEA" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Service-based Awards </link:label>
<link:label id="lab_it_ServiceBasedAwardsMember_93082FEDEFD9DE8054443FEE57AE7AEA_label_en-US" xlink:label="lab_it_ServiceBasedAwardsMember_93082FEDEFD9DE8054443FEE57AE7AEA" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Service Based Awards [Member] </link:label>
<link:label id="lab_it_ServiceBasedAwardsMember_93082FEDEFD9DE8054443FEE57AE7AEA_documentation_en-US" xlink:label="lab_it_ServiceBasedAwardsMember_93082FEDEFD9DE8054443FEE57AE7AEA" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US"> -- None. No documentation exists for this element. -- </link:label>
<link:loc xlink:href="it-20161231.xsd#it_ServiceBasedAwardsMember" xlink:label="loc_it_ServiceBasedAwardsMember_93082FEDEFD9DE8054443FEE57AE7AEA" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_it_ServiceBasedAwardsMember_93082FEDEFD9DE8054443FEE57AE7AEA" xlink:to="lab_it_ServiceBasedAwardsMember_93082FEDEFD9DE8054443FEE57AE7AEA" xlink:type="arc"/>
<link:label id="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized_EC1932E47D38B6D2094C3FEE57AE5E70_terseLabel_en-US" xlink:label="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized_EC1932E47D38B6D2094C3FEE57AE5E70" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Number of shares available for grant </link:label>
<link:label id="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized_EC1932E47D38B6D2094C3FEE57AE5E70_label_en-US" xlink:label="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized_EC1932E47D38B6D2094C3FEE57AE5E70" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized_EC1932E47D38B6D2094C3FEE57AE5E70" xlink:type="locator"/>
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<link:label id="lab_us-gaap_ShareBasedCompensation_8CD66E208F7D16A355373FEE57AE63B8_terseLabel_en-US" xlink:label="lab_us-gaap_ShareBasedCompensation_8CD66E208F7D16A355373FEE57AE63B8" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Stock-based compensation expense </link:label>
<link:label id="lab_us-gaap_ShareBasedCompensation_8CD66E208F7D16A355373FEE57AE63B8_label_en-US" xlink:label="lab_us-gaap_ShareBasedCompensation_8CD66E208F7D16A355373FEE57AE63B8" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Share-based Compensation </link:label>
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<link:label id="lab_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized_6CD48F3B53608B8151793FEE57AE42F4_terseLabel_en-US" xlink:label="lab_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized_6CD48F3B53608B8151793FEE57AE42F4" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Total share-based compensation cost not yet recognized </link:label>
<link:label id="lab_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized_6CD48F3B53608B8151793FEE57AE42F4_label_en-US" xlink:label="lab_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized_6CD48F3B53608B8151793FEE57AE42F4" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized_6CD48F3B53608B8151793FEE57AE42F4" xlink:type="locator"/>
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<link:label id="lab_it_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantedInPeriodWeightedAverageRemainingContractualTerm_D1BE448BA7F885C5F81B3FEE57AEC174_verboseLabel_en-US" xlink:label="lab_it_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantedInPeriodWeightedAverageRemainingContractualTerm_D1BE448BA7F885C5F81B3FEE57AEC174" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:type="resource" xml:lang="en-US"> Remaining weighted average service period </link:label>
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<link:label id="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1_28A2F803E7EE17AF67DA3FEE57AEA842_terseLabel_en-US" xlink:label="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1_28A2F803E7EE17AF67DA3FEE57AEA842" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Award vesting period </link:label>
<link:label id="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1_28A2F803E7EE17AF67DA3FEE57AEA842_label_en-US" xlink:label="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1_28A2F803E7EE17AF67DA3FEE57AEA842" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1_28A2F803E7EE17AF67DA3FEE57AEA842" xlink:type="locator"/>
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<link:label id="lab_it_ShareBasedCompensationArrangementByShareBasedPaymentAwardExpiryPeriodFromDateOfGrant_8608527F01D4FB4B85D63FEE57AEDD5D_terseLabel_en-US" xlink:label="lab_it_ShareBasedCompensationArrangementByShareBasedPaymentAwardExpiryPeriodFromDateOfGrant_8608527F01D4FB4B85D63FEE57AEDD5D" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Award expiry period from date of grant </link:label>
<link:label id="lab_it_ShareBasedCompensationArrangementByShareBasedPaymentAwardExpiryPeriodFromDateOfGrant_8608527F01D4FB4B85D63FEE57AEDD5D_label_en-US" xlink:label="lab_it_ShareBasedCompensationArrangementByShareBasedPaymentAwardExpiryPeriodFromDateOfGrant_8608527F01D4FB4B85D63FEE57AEDD5D" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Share Based Compensation Arrangement By Share Based Payment Award Expiry Period From Date Of Grant </link:label>
<link:label id="lab_it_ShareBasedCompensationArrangementByShareBasedPaymentAwardExpiryPeriodFromDateOfGrant_8608527F01D4FB4B85D63FEE57AEDD5D_documentation_en-US" xlink:label="lab_it_ShareBasedCompensationArrangementByShareBasedPaymentAwardExpiryPeriodFromDateOfGrant_8608527F01D4FB4B85D63FEE57AEDD5D" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US"> Share based compensation arrangement by share based payment award expiry period from date of grant. </link:label>
<link:loc xlink:href="it-20161231.xsd#it_ShareBasedCompensationArrangementByShareBasedPaymentAwardExpiryPeriodFromDateOfGrant" xlink:label="loc_it_ShareBasedCompensationArrangementByShareBasedPaymentAwardExpiryPeriodFromDateOfGrant_8608527F01D4FB4B85D63FEE57AEDD5D" xlink:type="locator"/>
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<link:label id="lab_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1_4E648C0F9918031D4F3E3FEE57AE5A94_terseLabel_en-US" xlink:label="lab_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1_4E648C0F9918031D4F3E3FEE57AE5A94" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Total compensation cost not yet recognized, period for recognition </link:label>
<link:label id="lab_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1_4E648C0F9918031D4F3E3FEE57AE5A94_label_en-US" xlink:label="lab_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1_4E648C0F9918031D4F3E3FEE57AE5A94" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1_4E648C0F9918031D4F3E3FEE57AE5A94" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1_4E648C0F9918031D4F3E3FEE57AE5A94" xlink:to="lab_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1_4E648C0F9918031D4F3E3FEE57AE5A94" xlink:type="arc"/>
<link:label id="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_2B2A2CDDBFA7813DCE5D3FEE57AEAC3E_terseLabel_en-US" xlink:label="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_2B2A2CDDBFA7813DCE5D3FEE57AEAC3E" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Equity instruments number of shares unvested (in shares) </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_2B2A2CDDBFA7813DCE5D3FEE57AEAC3E" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_2B2A2CDDBFA7813DCE5D3FEE57AEAC3E" xlink:to="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_2B2A2CDDBFA7813DCE5D3FEE57AEAC3E" xlink:type="arc"/>
<link:label id="lab_it_ShareBasedCompensationArrangementbyShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsOutstandingIntrinsicValue._3D77B44DBDF5E66333213FEE57AEC53F_terseLabel_en-US" xlink:label="lab_it_ShareBasedCompensationArrangementbyShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsOutstandingIntrinsicValue._3D77B44DBDF5E66333213FEE57AEC53F" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Aggregate intrinsic value of outstanding shares </link:label>
<link:label id="lab_it_ShareBasedCompensationArrangementbyShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsOutstandingIntrinsicValue._3D77B44DBDF5E66333213FEE57AEC53F_label_en-US" xlink:label="lab_it_ShareBasedCompensationArrangementbyShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsOutstandingIntrinsicValue._3D77B44DBDF5E66333213FEE57AEC53F" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Share Based Compensation Arrangement by Share Based Payment Award, Equity Instruments Other Than Options, Outstanding, Intrinsic Value. </link:label>
<link:label id="lab_it_ShareBasedCompensationArrangementbyShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsOutstandingIntrinsicValue._3D77B44DBDF5E66333213FEE57AEC53F_documentation_en-US" xlink:label="lab_it_ShareBasedCompensationArrangementbyShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsOutstandingIntrinsicValue._3D77B44DBDF5E66333213FEE57AEC53F" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US"> Share Based Compensation Arrangement by Share Based Payment Award, Equity Instruments Other Than Options, Outstanding, Intrinsic Value. </link:label>
<link:loc xlink:href="it-20161231.xsd#it_ShareBasedCompensationArrangementbyShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsOutstandingIntrinsicValue." xlink:label="loc_it_ShareBasedCompensationArrangementbyShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsOutstandingIntrinsicValue._3D77B44DBDF5E66333213FEE57AEC53F" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_it_ShareBasedCompensationArrangementbyShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsOutstandingIntrinsicValue._3D77B44DBDF5E66333213FEE57AEC53F" xlink:to="lab_it_ShareBasedCompensationArrangementbyShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsOutstandingIntrinsicValue._3D77B44DBDF5E66333213FEE57AEC53F" xlink:type="arc"/>
<link:label id="lab_it_SharebasedCompensationArrangementbySharebasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedandExpectedtoVestExercisableAggregateIntrinsicValue._BCB096CC0DA66094E0953FEE57AE994E_terseLabel_en-US" xlink:label="lab_it_SharebasedCompensationArrangementbySharebasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedandExpectedtoVestExercisableAggregateIntrinsicValue._BCB096CC0DA66094E0953FEE57AE994E" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Aggregate intrinsic value of shares vested and exercisable </link:label>
<link:label id="lab_it_SharebasedCompensationArrangementbySharebasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedandExpectedtoVestExercisableAggregateIntrinsicValue._BCB096CC0DA66094E0953FEE57AE994E_label_en-US" xlink:label="lab_it_SharebasedCompensationArrangementbySharebasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedandExpectedtoVestExercisableAggregateIntrinsicValue._BCB096CC0DA66094E0953FEE57AE994E" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Share based Compensation Arrangement by Share based Payment Award, Equity Instruments Other Than Options, Vested and Expected to Vest, Exercisable, Aggregate Intrinsic Value. </link:label>
<link:label id="lab_it_SharebasedCompensationArrangementbySharebasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedandExpectedtoVestExercisableAggregateIntrinsicValue._BCB096CC0DA66094E0953FEE57AE994E_documentation_en-US" xlink:label="lab_it_SharebasedCompensationArrangementbySharebasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedandExpectedtoVestExercisableAggregateIntrinsicValue._BCB096CC0DA66094E0953FEE57AE994E" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US"> Share based Compensation Arrangement by Share based Payment Award, Equity Instruments Other Than Options, Vested and Expected to Vest, Exercisable, Aggregate Intrinsic Value. </link:label>
<link:loc xlink:href="it-20161231.xsd#it_SharebasedCompensationArrangementbySharebasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedandExpectedtoVestExercisableAggregateIntrinsicValue." xlink:label="loc_it_SharebasedCompensationArrangementbySharebasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedandExpectedtoVestExercisableAggregateIntrinsicValue._BCB096CC0DA66094E0953FEE57AE994E" xlink:type="locator"/>
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<link:label id="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_F9964AC41994D95DE6403FEE57AE4839_terseLabel_en-US" xlink:label="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_F9964AC41994D95DE6403FEE57AE4839" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Grants during period (in shares) </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_F9964AC41994D95DE6403FEE57AE4839" xlink:type="locator"/>
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<link:label id="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsOutstandingWeightedAverageRemainingContractualTerms_628DFACC7D08EF32A4773FEE57AE73B2_terseLabel_en-US" xlink:label="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsOutstandingWeightedAverageRemainingContractualTerms_628DFACC7D08EF32A4773FEE57AE73B2" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Weighted average remaining contractual term </link:label>
<link:label id="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsOutstandingWeightedAverageRemainingContractualTerms_628DFACC7D08EF32A4773FEE57AE73B2_label_en-US" xlink:label="lab_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsOutstandingWeightedAverageRemainingContractualTerms_628DFACC7D08EF32A4773FEE57AE73B2" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Outstanding, Weighted Average Remaining Contractual Terms </link:label>
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<link:label id="lab_it_BaseFeePercentage_6867B0AEB0990050A3433FEE57AE3799_terseLabel_en-US" xlink:label="lab_it_BaseFeePercentage_6867B0AEB0990050A3433FEE57AE3799" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Base fee percentage </link:label>
<link:label id="lab_it_BaseFeePercentage_6867B0AEB0990050A3433FEE57AE3799_label_en-US" xlink:label="lab_it_BaseFeePercentage_6867B0AEB0990050A3433FEE57AE3799" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Base Fee Percentage </link:label>
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<link:label id="lab_us-gaap_ScheduleOfCompensationCostForShareBasedPaymentArrangementsAllocationOfShareBasedCompensationCostsByPlanTableTextBlock_29DC613C452557C4A20AE53BFC8F7338_terseLabel_en-US" xlink:label="lab_us-gaap_ScheduleOfCompensationCostForShareBasedPaymentArrangementsAllocationOfShareBasedCompensationCostsByPlanTableTextBlock_29DC613C452557C4A20AE53BFC8F7338" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Schedule of Stock-based Compensation Expense by Award Type </link:label>
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<link:label id="lab_us-gaap_DefinedContributionPlanMaximumAnnualContributionsPerEmployeeAmount_05022164E428393D4B133FEE568A9607_terseLabel_en-US" xlink:label="lab_us-gaap_DefinedContributionPlanMaximumAnnualContributionsPerEmployeeAmount_05022164E428393D4B133FEE568A9607" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Maximum annual contribution per employee, amount </link:label>
<link:label id="lab_us-gaap_DefinedContributionPlanMaximumAnnualContributionsPerEmployeeAmount_05022164E428393D4B133FEE568A9607_label_en-US" xlink:label="lab_us-gaap_DefinedContributionPlanMaximumAnnualContributionsPerEmployeeAmount_05022164E428393D4B133FEE568A9607" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Defined Contribution Plan, Maximum Annual Contributions Per Employee, Amount </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_DefinedContributionPlanMaximumAnnualContributionsPerEmployeeAmount" xlink:label="loc_us-gaap_DefinedContributionPlanMaximumAnnualContributionsPerEmployeeAmount_05022164E428393D4B133FEE568A9607" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DefinedContributionPlanMaximumAnnualContributionsPerEmployeeAmount_05022164E428393D4B133FEE568A9607" xlink:to="lab_us-gaap_DefinedContributionPlanMaximumAnnualContributionsPerEmployeeAmount_05022164E428393D4B133FEE568A9607" xlink:type="arc"/>
<link:label id="lab_us-gaap_DefinedContributionPlanCostRecognized_AEAEC812A3C7F784F50F3FEE568A4B81_terseLabel_en-US" xlink:label="lab_us-gaap_DefinedContributionPlanCostRecognized_AEAEC812A3C7F784F50F3FEE568A4B81" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Defined contribution plan cost recognized </link:label>
<link:label id="lab_us-gaap_DefinedContributionPlanCostRecognized_AEAEC812A3C7F784F50F3FEE568A4B81_label_en-US" xlink:label="lab_us-gaap_DefinedContributionPlanCostRecognized_AEAEC812A3C7F784F50F3FEE568A4B81" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Defined Contribution Plan, Cost Recognized </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_DefinedContributionPlanCostRecognized" xlink:label="loc_us-gaap_DefinedContributionPlanCostRecognized_AEAEC812A3C7F784F50F3FEE568A4B81" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DefinedContributionPlanCostRecognized_AEAEC812A3C7F784F50F3FEE568A4B81" xlink:to="lab_us-gaap_DefinedContributionPlanCostRecognized_AEAEC812A3C7F784F50F3FEE568A4B81" xlink:type="arc"/>
<link:label id="lab_us-gaap_DeferredCompensationLiabilityClassifiedNoncurrent_027FA9DAF72B8B0CC7513FEE568A2D88_terseLabel_en-US" xlink:label="lab_us-gaap_DeferredCompensationLiabilityClassifiedNoncurrent_027FA9DAF72B8B0CC7513FEE568A2D88" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Deferred compensation liability </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_DeferredCompensationLiabilityClassifiedNoncurrent" xlink:label="loc_us-gaap_DeferredCompensationLiabilityClassifiedNoncurrent_027FA9DAF72B8B0CC7513FEE568A2D88" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DeferredCompensationLiabilityClassifiedNoncurrent_027FA9DAF72B8B0CC7513FEE568A2D88" xlink:to="lab_us-gaap_DeferredCompensationLiabilityClassifiedNoncurrent_027FA9DAF72B8B0CC7513FEE568A2D88" xlink:type="arc"/>
<link:label id="lab_us-gaap_DeferredCompensationArrangementWithIndividualCompensationExpense_03BB454E3E0996B54FCD3FEE568A14B0_terseLabel_en-US" xlink:label="lab_us-gaap_DeferredCompensationArrangementWithIndividualCompensationExpense_03BB454E3E0996B54FCD3FEE568A14B0" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Compensation expense related to deferred compensation plan </link:label>
<link:label id="lab_us-gaap_DeferredCompensationArrangementWithIndividualCompensationExpense_03BB454E3E0996B54FCD3FEE568A14B0_label_en-US" xlink:label="lab_us-gaap_DeferredCompensationArrangementWithIndividualCompensationExpense_03BB454E3E0996B54FCD3FEE568A14B0" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Deferred Compensation Arrangement with Individual, Compensation Expense </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_DeferredCompensationArrangementWithIndividualCompensationExpense" xlink:label="loc_us-gaap_DeferredCompensationArrangementWithIndividualCompensationExpense_03BB454E3E0996B54FCD3FEE568A14B0" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DeferredCompensationArrangementWithIndividualCompensationExpense_03BB454E3E0996B54FCD3FEE568A14B0" xlink:to="lab_us-gaap_DeferredCompensationArrangementWithIndividualCompensationExpense_03BB454E3E0996B54FCD3FEE568A14B0" xlink:type="arc"/>
<link:label id="lab_us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsNextTwelveMonths_6BDC4AAC7CC9896013933FEE568C56D5_terseLabel_en-US" xlink:label="lab_us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsNextTwelveMonths_6BDC4AAC7CC9896013933FEE568C56D5" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Expected future benefit payments, in 2017 </link:label>
<link:label id="lab_us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsNextTwelveMonths_6BDC4AAC7CC9896013933FEE568C56D5_label_en-US" xlink:label="lab_us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsNextTwelveMonths_6BDC4AAC7CC9896013933FEE568C56D5" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Defined Benefit Plan, Expected Future Benefit Payments, Next Twelve Months </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsNextTwelveMonths" xlink:label="loc_us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsNextTwelveMonths_6BDC4AAC7CC9896013933FEE568C56D5" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsNextTwelveMonths_6BDC4AAC7CC9896013933FEE568C56D5" xlink:to="lab_us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsNextTwelveMonths_6BDC4AAC7CC9896013933FEE568C56D5" xlink:type="arc"/>
<link:label id="lab_us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearTwo_67008127C8B5E81CC6FB3FEE568CE040_terseLabel_en-US" xlink:label="lab_us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearTwo_67008127C8B5E81CC6FB3FEE568CE040" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Expected future benefit payments, in 2018 </link:label>
<link:label id="lab_us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearTwo_67008127C8B5E81CC6FB3FEE568CE040_label_en-US" xlink:label="lab_us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearTwo_67008127C8B5E81CC6FB3FEE568CE040" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Defined Benefit Plan, Expected Future Benefit Payments, Year Two </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearTwo" xlink:label="loc_us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearTwo_67008127C8B5E81CC6FB3FEE568CE040" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearTwo_67008127C8B5E81CC6FB3FEE568CE040" xlink:to="lab_us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearTwo_67008127C8B5E81CC6FB3FEE568CE040" xlink:type="arc"/>
<link:label id="lab_us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearThree_CBB3021F72CCE96DB0203FEE568C1DAF_terseLabel_en-US" xlink:label="lab_us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearThree_CBB3021F72CCE96DB0203FEE568C1DAF" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Expected future benefit payments, in 2019 </link:label>
<link:label id="lab_us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearThree_CBB3021F72CCE96DB0203FEE568C1DAF_label_en-US" xlink:label="lab_us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearThree_CBB3021F72CCE96DB0203FEE568C1DAF" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Defined Benefit Plan, Expected Future Benefit Payments, Year Three </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearThree" xlink:label="loc_us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearThree_CBB3021F72CCE96DB0203FEE568C1DAF" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearThree_CBB3021F72CCE96DB0203FEE568C1DAF" xlink:to="lab_us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearThree_CBB3021F72CCE96DB0203FEE568C1DAF" xlink:type="arc"/>
<link:label id="lab_us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearFour_1FD68C7C22B8CF1A32103FEE568C2EDE_terseLabel_en-US" xlink:label="lab_us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearFour_1FD68C7C22B8CF1A32103FEE568C2EDE" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Expected future benefit payments, in 2020 </link:label>
<link:label id="lab_us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearFour_1FD68C7C22B8CF1A32103FEE568C2EDE_label_en-US" xlink:label="lab_us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearFour_1FD68C7C22B8CF1A32103FEE568C2EDE" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Defined Benefit Plan, Expected Future Benefit Payments, Year Four </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearFour" xlink:label="loc_us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearFour_1FD68C7C22B8CF1A32103FEE568C2EDE" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearFour_1FD68C7C22B8CF1A32103FEE568C2EDE" xlink:to="lab_us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearFour_1FD68C7C22B8CF1A32103FEE568C2EDE" xlink:type="arc"/>
<link:label id="lab_us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearFive_685B6A05BEAAD16646B53FEE568CA0DE_terseLabel_en-US" xlink:label="lab_us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearFive_685B6A05BEAAD16646B53FEE568CA0DE" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Expected future benefit payments, in 2021 </link:label>
<link:label id="lab_us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearFive_685B6A05BEAAD16646B53FEE568CA0DE_label_en-US" xlink:label="lab_us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearFive_685B6A05BEAAD16646B53FEE568CA0DE" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Defined Benefit Plan, Expected Future Benefit Payments, Year Five </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearFive" xlink:label="loc_us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearFive_685B6A05BEAAD16646B53FEE568CA0DE" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearFive_685B6A05BEAAD16646B53FEE568CA0DE" xlink:to="lab_us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsYearFive_685B6A05BEAAD16646B53FEE568CA0DE" xlink:type="arc"/>
<link:label id="lab_us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsFiveFiscalYearsThereafter_1DB548DA861EDF3DB8D03FEE568CF15B_terseLabel_en-US" xlink:label="lab_us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsFiveFiscalYearsThereafter_1DB548DA861EDF3DB8D03FEE568CF15B" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Expected future benefit payments in the five years thereafter </link:label>
<link:label id="lab_us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsFiveFiscalYearsThereafter_1DB548DA861EDF3DB8D03FEE568CF15B_label_en-US" xlink:label="lab_us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsFiveFiscalYearsThereafter_1DB548DA861EDF3DB8D03FEE568CF15B" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Defined Benefit Plan, Expected Future Benefit Payments, Five Fiscal Years Thereafter </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsFiveFiscalYearsThereafter" xlink:label="loc_us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsFiveFiscalYearsThereafter_1DB548DA861EDF3DB8D03FEE568CF15B" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsFiveFiscalYearsThereafter_1DB548DA861EDF3DB8D03FEE568CF15B" xlink:to="lab_us-gaap_DefinedBenefitPlanExpectedFutureBenefitPaymentsFiveFiscalYearsThereafter_1DB548DA861EDF3DB8D03FEE568CF15B" xlink:type="arc"/>
<link:label id="lab_us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostExpectedLongTermReturnOnAssets_D1191A476F5C7962BDCF3FEE568CD606_terseLabel_en-US" xlink:label="lab_us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostExpectedLongTermReturnOnAssets_D1191A476F5C7962BDCF3FEE568CD606" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Expected long-term return on assets </link:label>
<link:label id="lab_us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostExpectedLongTermReturnOnAssets_D1191A476F5C7962BDCF3FEE568CD606_label_en-US" xlink:label="lab_us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostExpectedLongTermReturnOnAssets_D1191A476F5C7962BDCF3FEE568CD606" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Expected Long-term Return on Assets </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostExpectedLongTermReturnOnAssets" xlink:label="loc_us-gaap_DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostExpectedLongTermReturnOnAssets_D1191A476F5C7962BDCF3FEE568CD606" xlink:type="locator"/>
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<link:label id="lab_us-gaap_DefinedBenefitPlanContributionsByEmployer_30ECBC6D7F7CF84FEF0D3FEE568C4265_terseLabel_en-US" xlink:label="lab_us-gaap_DefinedBenefitPlanContributionsByEmployer_30ECBC6D7F7CF84FEF0D3FEE568C4265" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Contributions by employer </link:label>
<link:label id="lab_us-gaap_DefinedBenefitPlanContributionsByEmployer_30ECBC6D7F7CF84FEF0D3FEE568C4265_label_en-US" xlink:label="lab_us-gaap_DefinedBenefitPlanContributionsByEmployer_30ECBC6D7F7CF84FEF0D3FEE568C4265" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Defined Benefit Plan, Contributions by Employer </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_DefinedBenefitPlanContributionsByEmployer" xlink:label="loc_us-gaap_DefinedBenefitPlanContributionsByEmployer_30ECBC6D7F7CF84FEF0D3FEE568C4265" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DefinedBenefitPlanContributionsByEmployer_30ECBC6D7F7CF84FEF0D3FEE568C4265" xlink:to="lab_us-gaap_DefinedBenefitPlanContributionsByEmployer_30ECBC6D7F7CF84FEF0D3FEE568C4265" xlink:type="arc"/>
<link:label id="lab_us-gaap_DefinedBenefitPlanBenefitsPaid_A71BDC9B3029EB3A95F33FEE568CE79E_verboseLabel_en-US" xlink:label="lab_us-gaap_DefinedBenefitPlanBenefitsPaid_A71BDC9B3029EB3A95F33FEE568CE79E" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:type="resource" xml:lang="en-US"> Benefits paid to participants under defined benefit plans </link:label>
<link:label id="lab_us-gaap_DefinedBenefitPlanBenefitsPaid_A71BDC9B3029EB3A95F33FEE568CE79E_label_en-US" xlink:label="lab_us-gaap_DefinedBenefitPlanBenefitsPaid_A71BDC9B3029EB3A95F33FEE568CE79E" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Defined Benefit Plan, Benefits Paid </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_DefinedBenefitPlanBenefitsPaid" xlink:label="loc_us-gaap_DefinedBenefitPlanBenefitsPaid_A71BDC9B3029EB3A95F33FEE568CE79E" xlink:type="locator"/>
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<link:label id="lab_it_WeightedAverageAmortizationPeriod_1DFADFC832C79FCC86053FEE568CC42B_terseLabel_en-US" xlink:label="lab_it_WeightedAverageAmortizationPeriod_1DFADFC832C79FCC86053FEE568CC42B" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Weighted average amortization period </link:label>
<link:label id="lab_it_WeightedAverageAmortizationPeriod_1DFADFC832C79FCC86053FEE568CC42B_label_en-US" xlink:label="lab_it_WeightedAverageAmortizationPeriod_1DFADFC832C79FCC86053FEE568CC42B" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Weighted Average Amortization Period </link:label>
<link:label id="lab_it_WeightedAverageAmortizationPeriod_1DFADFC832C79FCC86053FEE568CC42B_documentation_en-US" xlink:label="lab_it_WeightedAverageAmortizationPeriod_1DFADFC832C79FCC86053FEE568CC42B" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US"> Weighted Average Amortization Period </link:label>
<link:loc xlink:href="it-20161231.xsd#it_WeightedAverageAmortizationPeriod" xlink:label="loc_it_WeightedAverageAmortizationPeriod_1DFADFC832C79FCC86053FEE568CC42B" xlink:type="locator"/>
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<link:label id="lab_us-gaap_DefinedBenefitPlanFutureAmortizationOfGainLoss_75D6AEA548A517341C033FEE568C83DA_terseLabel_en-US" xlink:label="lab_us-gaap_DefinedBenefitPlanFutureAmortizationOfGainLoss_75D6AEA548A517341C033FEE568C83DA" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Future amortization of unrecognized gains losses </link:label>
<link:label id="lab_us-gaap_DefinedBenefitPlanFutureAmortizationOfGainLoss_75D6AEA548A517341C033FEE568C83DA_label_en-US" xlink:label="lab_us-gaap_DefinedBenefitPlanFutureAmortizationOfGainLoss_75D6AEA548A517341C033FEE568C83DA" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Defined Benefit Plan, Future Amortization of Gain (Loss) </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_DefinedBenefitPlanFutureAmortizationOfGainLoss" xlink:label="loc_us-gaap_DefinedBenefitPlanFutureAmortizationOfGainLoss_75D6AEA548A517341C033FEE568C83DA" xlink:type="locator"/>
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<link:label id="lab_us-gaap_OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetGainLossNetOfTax_4C09D534F0BDDBB944EF3FEE568CB996_terseLabel_en-US" xlink:label="lab_us-gaap_OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetGainLossNetOfTax_4C09D534F0BDDBB944EF3FEE568CB996" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Amortization of deferred actuarial losses from AOCL/I </link:label>
<link:label id="lab_us-gaap_OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetGainLossNetOfTax_4C09D534F0BDDBB944EF3FEE568CB996_label_en-US" xlink:label="lab_us-gaap_OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetGainLossNetOfTax_4C09D534F0BDDBB944EF3FEE568CB996" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI, Pension and Other Postretirement Benefit Plans, for Net Gain (Loss), Net of Tax </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetGainLossNetOfTax" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetGainLossNetOfTax_4C09D534F0BDDBB944EF3FEE568CB996" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetGainLossNetOfTax_4C09D534F0BDDBB944EF3FEE568CB996" xlink:to="lab_us-gaap_OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetGainLossNetOfTax_4C09D534F0BDDBB944EF3FEE568CB996" xlink:type="arc"/>
<link:label id="lab_it_DefinedBenefitPlanReinsuranceAsset_94392A78471372D6AA343FEE568CB790_terseLabel_en-US" xlink:label="lab_it_DefinedBenefitPlanReinsuranceAsset_94392A78471372D6AA343FEE568CB790" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Other assets </link:label>
<link:label id="lab_it_DefinedBenefitPlanReinsuranceAsset_94392A78471372D6AA343FEE568CB790_label_en-US" xlink:label="lab_it_DefinedBenefitPlanReinsuranceAsset_94392A78471372D6AA343FEE568CB790" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Defined Benefit Plan, Reinsurance Asset </link:label>
<link:label id="lab_it_DefinedBenefitPlanReinsuranceAsset_94392A78471372D6AA343FEE568CB790_documentation_en-US" xlink:label="lab_it_DefinedBenefitPlanReinsuranceAsset_94392A78471372D6AA343FEE568CB790" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US"> Defined Benefit Plan, Reinsurance Asset </link:label>
<link:loc xlink:href="it-20161231.xsd#it_DefinedBenefitPlanReinsuranceAsset" xlink:label="loc_it_DefinedBenefitPlanReinsuranceAsset_94392A78471372D6AA343FEE568CB790" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_it_DefinedBenefitPlanReinsuranceAsset_94392A78471372D6AA343FEE568CB790" xlink:to="lab_it_DefinedBenefitPlanReinsuranceAsset_94392A78471372D6AA343FEE568CB790" xlink:type="arc"/>
<link:label id="lab_us-gaap_StockholdersEquityNoteDisclosureTextBlock_0C2D41496685B764E0153ED1D5E5BBC2_terseLabel_en-US" xlink:label="lab_us-gaap_StockholdersEquityNoteDisclosureTextBlock_0C2D41496685B764E0153ED1D5E5BBC2" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> STOCKHOLDERS’ EQUITY (DEFICIT) </link:label>
<link:label id="lab_us-gaap_StockholdersEquityNoteDisclosureTextBlock_0C2D41496685B764E0153ED1D5E5BBC2_label_en-US" xlink:label="lab_us-gaap_StockholdersEquityNoteDisclosureTextBlock_0C2D41496685B764E0153ED1D5E5BBC2" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Stockholders' Equity Note Disclosure [Text Block] </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_StockholdersEquityNoteDisclosureTextBlock" xlink:label="loc_us-gaap_StockholdersEquityNoteDisclosureTextBlock_0C2D41496685B764E0153ED1D5E5BBC2" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_StockholdersEquityNoteDisclosureTextBlock_0C2D41496685B764E0153ED1D5E5BBC2" xlink:to="lab_us-gaap_StockholdersEquityNoteDisclosureTextBlock_0C2D41496685B764E0153ED1D5E5BBC2" xlink:type="arc"/>
<link:label id="lab_it_BusinessandSignificantAccountingPoliciesTable_2D750F4AB3BEEED694C33E9436EF027B_terseLabel_en-US" xlink:label="lab_it_BusinessandSignificantAccountingPoliciesTable_2D750F4AB3BEEED694C33E9436EF027B" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Business and Significant Accounting Policies [Table] </link:label>
<link:label id="lab_it_BusinessandSignificantAccountingPoliciesTable_2D750F4AB3BEEED694C33E9436EF027B_label_en-US" xlink:label="lab_it_BusinessandSignificantAccountingPoliciesTable_2D750F4AB3BEEED694C33E9436EF027B" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Business and Significant Accounting Policies [Table] </link:label>
<link:label id="lab_it_BusinessandSignificantAccountingPoliciesTable_2D750F4AB3BEEED694C33E9436EF027B_documentation_en-US" xlink:label="lab_it_BusinessandSignificantAccountingPoliciesTable_2D750F4AB3BEEED694C33E9436EF027B" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US"> Business and Significant Accounting Policies [Table] </link:label>
<link:loc xlink:href="it-20161231.xsd#it_BusinessandSignificantAccountingPoliciesTable" xlink:label="loc_it_BusinessandSignificantAccountingPoliciesTable_2D750F4AB3BEEED694C33E9436EF027B" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_it_BusinessandSignificantAccountingPoliciesTable_2D750F4AB3BEEED694C33E9436EF027B" xlink:to="lab_it_BusinessandSignificantAccountingPoliciesTable_2D750F4AB3BEEED694C33E9436EF027B" xlink:type="arc"/>
<link:label id="lab_it_SoftwareAdviceInc.MarketVisioOyandSircleITInc.Member_009A70A57146B52DD8E93E9436EFE67C_terseLabel_en-US" xlink:label="lab_it_SoftwareAdviceInc.MarketVisioOyandSircleITInc.Member_009A70A57146B52DD8E93E9436EFE67C" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Software Advice, Inc., Market-Visio Oy, and SircleIT Inc. </link:label>
<link:label id="lab_it_SoftwareAdviceInc.MarketVisioOyandSircleITInc.Member_009A70A57146B52DD8E93E9436EFE67C_label_en-US" xlink:label="lab_it_SoftwareAdviceInc.MarketVisioOyandSircleITInc.Member_009A70A57146B52DD8E93E9436EFE67C" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Software Advice, Inc., Market-Visio Oy, and SircleIT Inc. [Member] </link:label>
<link:label id="lab_it_SoftwareAdviceInc.MarketVisioOyandSircleITInc.Member_009A70A57146B52DD8E93E9436EFE67C_documentation_en-US" xlink:label="lab_it_SoftwareAdviceInc.MarketVisioOyandSircleITInc.Member_009A70A57146B52DD8E93E9436EFE67C" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US"> Software Advice, Inc., Market-Visio Oy, and SircleIT Inc. [Member] </link:label>
<link:loc xlink:href="it-20161231.xsd#it_SoftwareAdviceInc.MarketVisioOyandSircleITInc.Member" xlink:label="loc_it_SoftwareAdviceInc.MarketVisioOyandSircleITInc.Member_009A70A57146B52DD8E93E9436EFE67C" xlink:type="locator"/>
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<link:label id="lab_us-gaap_FinancialInstrumentAxis_E10DC43045942C4A59BA3E9436F030C6_terseLabel_en-US" xlink:label="lab_us-gaap_FinancialInstrumentAxis_E10DC43045942C4A59BA3E9436F030C6" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Financial Instrument [Axis] </link:label>
<link:label id="lab_us-gaap_FinancialInstrumentAxis_E10DC43045942C4A59BA3E9436F030C6_label_en-US" xlink:label="lab_us-gaap_FinancialInstrumentAxis_E10DC43045942C4A59BA3E9436F030C6" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Financial Instrument [Axis] </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_FinancialInstrumentAxis" xlink:label="loc_us-gaap_FinancialInstrumentAxis_E10DC43045942C4A59BA3E9436F030C6" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_FinancialInstrumentAxis_E10DC43045942C4A59BA3E9436F030C6" xlink:to="lab_us-gaap_FinancialInstrumentAxis_E10DC43045942C4A59BA3E9436F030C6" xlink:type="arc"/>
<link:label id="lab_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_DD28190E45B73892CFEF3E9436F013D6_terseLabel_en-US" xlink:label="lab_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_DD28190E45B73892CFEF3E9436F013D6" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Types of Financial Instruments [Domain] </link:label>
<link:label id="lab_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_DD28190E45B73892CFEF3E9436F013D6_label_en-US" xlink:label="lab_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_DD28190E45B73892CFEF3E9436F013D6" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Financial Instruments [Domain] </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_DD28190E45B73892CFEF3E9436F013D6" xlink:type="locator"/>
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<link:label id="lab_it_ForeignCurrencyExchangeContractsMember_ACEA3A838F2CA5D8321E3E9436F05063_terseLabel_en-US" xlink:label="lab_it_ForeignCurrencyExchangeContractsMember_ACEA3A838F2CA5D8321E3E9436F05063" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Foreign currency exchange contracts </link:label>
<link:label id="lab_it_ForeignCurrencyExchangeContractsMember_ACEA3A838F2CA5D8321E3E9436F05063_label_en-US" xlink:label="lab_it_ForeignCurrencyExchangeContractsMember_ACEA3A838F2CA5D8321E3E9436F05063" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Foreign Currency Exchange Contracts [Member] </link:label>
<link:label id="lab_it_ForeignCurrencyExchangeContractsMember_ACEA3A838F2CA5D8321E3E9436F05063_documentation_en-US" xlink:label="lab_it_ForeignCurrencyExchangeContractsMember_ACEA3A838F2CA5D8321E3E9436F05063" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US"> -- None. No documentation exists for this element. -- </link:label>
<link:loc xlink:href="it-20161231.xsd#it_ForeignCurrencyExchangeContractsMember" xlink:label="loc_it_ForeignCurrencyExchangeContractsMember_ACEA3A838F2CA5D8321E3E9436F05063" xlink:type="locator"/>
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<link:label id="lab_it_BusinessandSignificantAccountingPoliciesLineItems_BA0F6C68AF859176EE033E9436F03158_terseLabel_en-US" xlink:label="lab_it_BusinessandSignificantAccountingPoliciesLineItems_BA0F6C68AF859176EE033E9436F03158" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Business and Significant Accounting Policies [Line Items] </link:label>
<link:label id="lab_it_BusinessandSignificantAccountingPoliciesLineItems_BA0F6C68AF859176EE033E9436F03158_label_en-US" xlink:label="lab_it_BusinessandSignificantAccountingPoliciesLineItems_BA0F6C68AF859176EE033E9436F03158" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Business and Significant Accounting Policies [Line Items] </link:label>
<link:label id="lab_it_BusinessandSignificantAccountingPoliciesLineItems_BA0F6C68AF859176EE033E9436F03158_documentation_en-US" xlink:label="lab_it_BusinessandSignificantAccountingPoliciesLineItems_BA0F6C68AF859176EE033E9436F03158" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US"> [Line Items] for Business and Significant Accounting Policies [Table] </link:label>
<link:loc xlink:href="it-20161231.xsd#it_BusinessandSignificantAccountingPoliciesLineItems" xlink:label="loc_it_BusinessandSignificantAccountingPoliciesLineItems_BA0F6C68AF859176EE033E9436F03158" xlink:type="locator"/>
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<link:label id="lab_it_BusinessCombinationAcquisitionandIntegrationRelatedCosts_445C513D690F83EFF0D03E9436F0E996_terseLabel_en-US" xlink:label="lab_it_BusinessCombinationAcquisitionandIntegrationRelatedCosts_445C513D690F83EFF0D03E9436F0E996" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Acquisition and integration charges </link:label>
<link:label id="lab_it_BusinessCombinationAcquisitionandIntegrationRelatedCosts_445C513D690F83EFF0D03E9436F0E996_label_en-US" xlink:label="lab_it_BusinessCombinationAcquisitionandIntegrationRelatedCosts_445C513D690F83EFF0D03E9436F0E996" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Business Combination, Acquisition and Integration Related Costs </link:label>
<link:label id="lab_it_BusinessCombinationAcquisitionandIntegrationRelatedCosts_445C513D690F83EFF0D03E9436F0E996_documentation_en-US" xlink:label="lab_it_BusinessCombinationAcquisitionandIntegrationRelatedCosts_445C513D690F83EFF0D03E9436F0E996" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US"> Business Combination, Acquisition and Integration Related Costs </link:label>
<link:loc xlink:href="it-20161231.xsd#it_BusinessCombinationAcquisitionandIntegrationRelatedCosts" xlink:label="loc_it_BusinessCombinationAcquisitionandIntegrationRelatedCosts_445C513D690F83EFF0D03E9436F0E996" xlink:type="locator"/>
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<link:label id="lab_us-gaap_BusinessCombinationContingentConsiderationArrangementsChangeInAmountOfContingentConsiderationLiability1_C19537C93F280F632C473E9436F0E44D_negatedTerseLabel_en-US" xlink:label="lab_us-gaap_BusinessCombinationContingentConsiderationArrangementsChangeInAmountOfContingentConsiderationLiability1_C19537C93F280F632C473E9436F0E44D" xlink:role="http://www.xbrl.org/2009/role/negatedTerseLabel" xlink:type="resource" xml:lang="en-US"> Decrease in contingent liability </link:label>
<link:label id="lab_us-gaap_BusinessCombinationContingentConsiderationArrangementsChangeInAmountOfContingentConsiderationLiability1_C19537C93F280F632C473E9436F0E44D_label_en-US" xlink:label="lab_us-gaap_BusinessCombinationContingentConsiderationArrangementsChangeInAmountOfContingentConsiderationLiability1_C19537C93F280F632C473E9436F0E44D" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Business Combination, Contingent Consideration Arrangements, Change in Amount of Contingent Consideration, Liability </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_BusinessCombinationContingentConsiderationArrangementsChangeInAmountOfContingentConsiderationLiability1" xlink:label="loc_us-gaap_BusinessCombinationContingentConsiderationArrangementsChangeInAmountOfContingentConsiderationLiability1_C19537C93F280F632C473E9436F0E44D" xlink:type="locator"/>
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<link:label id="lab_us-gaap_UnbilledReceivablesCurrent_1FE9B8E77FE428EF82FC3E9436F0FB07_terseLabel_en-US" xlink:label="lab_us-gaap_UnbilledReceivablesCurrent_1FE9B8E77FE428EF82FC3E9436F0FB07" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Unbilled fees receivable </link:label>
<link:label id="lab_us-gaap_UnbilledReceivablesCurrent_1FE9B8E77FE428EF82FC3E9436F0FB07_label_en-US" xlink:label="lab_us-gaap_UnbilledReceivablesCurrent_1FE9B8E77FE428EF82FC3E9436F0FB07" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Unbilled Receivables, Current </link:label>
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<link:label id="lab_us-gaap_Depreciation_4C0CAE30064433D8D7933E9436F05EA9_verboseLabel_en-US" xlink:label="lab_us-gaap_Depreciation_4C0CAE30064433D8D7933E9436F05EA9" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:type="resource" xml:lang="en-US"> Depreciation expense </link:label>
<link:label id="lab_us-gaap_Depreciation_4C0CAE30064433D8D7933E9436F05EA9_label_en-US" xlink:label="lab_us-gaap_Depreciation_4C0CAE30064433D8D7933E9436F05EA9" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Depreciation </link:label>
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<link:label id="lab_us-gaap_CapitalizedComputerSoftwareNet_C1E34E2A7C60DA749B313E9436F060D1_terseLabel_en-US" xlink:label="lab_us-gaap_CapitalizedComputerSoftwareNet_C1E34E2A7C60DA749B313E9436F060D1" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Net capitalized development costs for internal use software </link:label>
<link:label id="lab_us-gaap_CapitalizedComputerSoftwareNet_C1E34E2A7C60DA749B313E9436F060D1_label_en-US" xlink:label="lab_us-gaap_CapitalizedComputerSoftwareNet_C1E34E2A7C60DA749B313E9436F060D1" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Capitalized Computer Software, Net </link:label>
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<link:label id="lab_us-gaap_CapitalizedComputerSoftwareAmortization1_74C7E2C91008917E308B3E9436F1EEAA_terseLabel_en-US" xlink:label="lab_us-gaap_CapitalizedComputerSoftwareAmortization1_74C7E2C91008917E308B3E9436F1EEAA" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Amortization of capitalized internal software development costs </link:label>
<link:label id="lab_us-gaap_CapitalizedComputerSoftwareAmortization1_74C7E2C91008917E308B3E9436F1EEAA_label_en-US" xlink:label="lab_us-gaap_CapitalizedComputerSoftwareAmortization1_74C7E2C91008917E308B3E9436F1EEAA" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Capitalized Computer Software, Amortization </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_CapitalizedComputerSoftwareAmortization1" xlink:label="loc_us-gaap_CapitalizedComputerSoftwareAmortization1_74C7E2C91008917E308B3E9436F1EEAA" xlink:type="locator"/>
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<link:label id="lab_us-gaap_FiniteLivedIntangibleAssetUsefulLife_1B4B9120299971899A2B3E9436F16F8E_terseLabel_en-US" xlink:label="lab_us-gaap_FiniteLivedIntangibleAssetUsefulLife_1B4B9120299971899A2B3E9436F16F8E" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Remaining amortization period </link:label>
<link:label id="lab_us-gaap_FiniteLivedIntangibleAssetUsefulLife_1B4B9120299971899A2B3E9436F16F8E_label_en-US" xlink:label="lab_us-gaap_FiniteLivedIntangibleAssetUsefulLife_1B4B9120299971899A2B3E9436F16F8E" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Finite-Lived Intangible Asset, Useful Life </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetUsefulLife" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetUsefulLife_1B4B9120299971899A2B3E9436F16F8E" xlink:type="locator"/>
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<link:label id="lab_us-gaap_AmortizationOfIntangibleAssets_1B56DB60AE149FA90EAA3E9436F1C69E_terseLabel_en-US" xlink:label="lab_us-gaap_AmortizationOfIntangibleAssets_1B56DB60AE149FA90EAA3E9436F1C69E" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Amortization of intangibles </link:label>
<link:label id="lab_us-gaap_AmortizationOfIntangibleAssets_1B56DB60AE149FA90EAA3E9436F1C69E_label_en-US" xlink:label="lab_us-gaap_AmortizationOfIntangibleAssets_1B56DB60AE149FA90EAA3E9436F1C69E" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Amortization of Intangible Assets </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_AmortizationOfIntangibleAssets" xlink:label="loc_us-gaap_AmortizationOfIntangibleAssets_1B56DB60AE149FA90EAA3E9436F1C69E" xlink:type="locator"/>
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<link:label id="lab_us-gaap_PensionExpense_01F672950BAF92B449173E9436F1370E_terseLabel_en-US" xlink:label="lab_us-gaap_PensionExpense_01F672950BAF92B449173E9436F1370E" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Pension expense </link:label>
<link:label id="lab_us-gaap_PensionExpense_01F672950BAF92B449173E9436F1370E_label_en-US" xlink:label="lab_us-gaap_PensionExpense_01F672950BAF92B449173E9436F1370E" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Pension Expense </link:label>
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<link:label id="lab_us-gaap_ForeignCurrencyTransactionGainLossRealized_CA25EF0FB974BC66AD783E9436F1603E_terseLabel_en-US" xlink:label="lab_us-gaap_ForeignCurrencyTransactionGainLossRealized_CA25EF0FB974BC66AD783E9436F1603E" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Foreign currency transaction gain (loss) </link:label>
<link:label id="lab_us-gaap_ForeignCurrencyTransactionGainLossRealized_CA25EF0FB974BC66AD783E9436F1603E_label_en-US" xlink:label="lab_us-gaap_ForeignCurrencyTransactionGainLossRealized_CA25EF0FB974BC66AD783E9436F1603E" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Foreign Currency Transaction Gain (Loss), Realized </link:label>
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<link:label id="lab_us-gaap_DerivativeGainLossOnDerivativeNet_EC0F7B094D951826670B3E9436F1F2F0_verboseLabel_en-US" xlink:label="lab_us-gaap_DerivativeGainLossOnDerivativeNet_EC0F7B094D951826670B3E9436F1F2F0" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:type="resource" xml:lang="en-US"> Derivative instruments, gain (loss) recognized in income, net </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_DerivativeGainLossOnDerivativeNet" xlink:label="loc_us-gaap_DerivativeGainLossOnDerivativeNet_EC0F7B094D951826670B3E9436F1F2F0" xlink:type="locator"/>
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<link:label id="lab_us-gaap_GoodwillImpairmentLoss_8AE13AEE68B7D8A58E243E9436F15C14_terseLabel_en-US" xlink:label="lab_us-gaap_GoodwillImpairmentLoss_8AE13AEE68B7D8A58E243E9436F15C14" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Goodwill, impairment loss </link:label>
<link:label id="lab_us-gaap_GoodwillImpairmentLoss_8AE13AEE68B7D8A58E243E9436F15C14_label_en-US" xlink:label="lab_us-gaap_GoodwillImpairmentLoss_8AE13AEE68B7D8A58E243E9436F15C14" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Goodwill, Impairment Loss </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_GoodwillImpairmentLoss" xlink:label="loc_us-gaap_GoodwillImpairmentLoss_8AE13AEE68B7D8A58E243E9436F15C14" xlink:type="locator"/>
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<link:label id="lab_us-gaap_ImpairmentOfLongLivedAssetsHeldForUse_4C2C765BFA61E6F8F1CA3E9436F181A3_terseLabel_en-US" xlink:label="lab_us-gaap_ImpairmentOfLongLivedAssetsHeldForUse_4C2C765BFA61E6F8F1CA3E9436F181A3" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Impairment of long-lived assets </link:label>
<link:label id="lab_us-gaap_ImpairmentOfLongLivedAssetsHeldForUse_4C2C765BFA61E6F8F1CA3E9436F181A3_label_en-US" xlink:label="lab_us-gaap_ImpairmentOfLongLivedAssetsHeldForUse_4C2C765BFA61E6F8F1CA3E9436F181A3" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Impairment of Long-Lived Assets Held-for-use </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ImpairmentOfLongLivedAssetsHeldForUse" xlink:label="loc_us-gaap_ImpairmentOfLongLivedAssetsHeldForUse_4C2C765BFA61E6F8F1CA3E9436F181A3" xlink:type="locator"/>
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<link:label id="lab_us-gaap_SegmentReportingDisclosureTextBlock_BACB35ECF24E7787B123E53BFC7661A1_terseLabel_en-US" xlink:label="lab_us-gaap_SegmentReportingDisclosureTextBlock_BACB35ECF24E7787B123E53BFC7661A1" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> SEGMENT INFORMATION </link:label>
<link:label id="lab_us-gaap_SegmentReportingDisclosureTextBlock_BACB35ECF24E7787B123E53BFC7661A1_label_en-US" xlink:label="lab_us-gaap_SegmentReportingDisclosureTextBlock_BACB35ECF24E7787B123E53BFC7661A1" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Segment Reporting Disclosure [Text Block] </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_SegmentReportingDisclosureTextBlock" xlink:label="loc_us-gaap_SegmentReportingDisclosureTextBlock_BACB35ECF24E7787B123E53BFC7661A1" xlink:type="locator"/>
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<link:label id="lab_us-gaap_DefinedBenefitPlanAssetsForPlanBenefitsNoncurrent_823CC7B473E6FF14A77E3FEE581CD339_terseLabel_en-US" xlink:label="lab_us-gaap_DefinedBenefitPlanAssetsForPlanBenefitsNoncurrent_823CC7B473E6FF14A77E3FEE581CD339" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Benefit plan-related assets </link:label>
<link:label id="lab_us-gaap_DefinedBenefitPlanAssetsForPlanBenefitsNoncurrent_823CC7B473E6FF14A77E3FEE581CD339_label_en-US" xlink:label="lab_us-gaap_DefinedBenefitPlanAssetsForPlanBenefitsNoncurrent_823CC7B473E6FF14A77E3FEE581CD339" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Defined Benefit Plan, Assets for Plan Benefits, Noncurrent </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_DefinedBenefitPlanAssetsForPlanBenefitsNoncurrent" xlink:label="loc_us-gaap_DefinedBenefitPlanAssetsForPlanBenefitsNoncurrent_823CC7B473E6FF14A77E3FEE581CD339" xlink:type="locator"/>
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<link:label id="lab_us-gaap_OtherAssetsMiscellaneousNoncurrent_A967F27303E816B0D8A53FEE581CF19F_terseLabel_en-US" xlink:label="lab_us-gaap_OtherAssetsMiscellaneousNoncurrent_A967F27303E816B0D8A53FEE581CF19F" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Other </link:label>
<link:label id="lab_us-gaap_OtherAssetsMiscellaneousNoncurrent_A967F27303E816B0D8A53FEE581CF19F_label_en-US" xlink:label="lab_us-gaap_OtherAssetsMiscellaneousNoncurrent_A967F27303E816B0D8A53FEE581CF19F" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Other Assets, Miscellaneous, Noncurrent </link:label>
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<link:label id="lab_us-gaap_OtherAssetsNoncurrent_14D3B639314F0AF57EBC3FEE581C4006_totalLabel_en-US" xlink:label="lab_us-gaap_OtherAssetsNoncurrent_14D3B639314F0AF57EBC3FEE581C4006" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:type="resource" xml:lang="en-US"> Total other assets </link:label>
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<link:label id="lab_us-gaap_StatementOfCashFlowsAbstract_33C8C6757B4079D41A143E9437086BFA_label_en-US" xlink:label="lab_us-gaap_StatementOfCashFlowsAbstract_33C8C6757B4079D41A143E9437086BFA" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Statement of Cash Flows [Abstract] </link:label>
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<link:label id="lab_us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract_9F686BF5D9907BF374D93E943708C91E_terseLabel_en-US" xlink:label="lab_us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract_9F686BF5D9907BF374D93E943708C91E" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Operating activities: </link:label>
<link:label id="lab_us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract_9F686BF5D9907BF374D93E943708C91E_label_en-US" xlink:label="lab_us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract_9F686BF5D9907BF374D93E943708C91E" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Net Cash Provided by (Used in) Operating Activities [Abstract] </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract" xlink:label="loc_us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract_9F686BF5D9907BF374D93E943708C91E" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract_9F686BF5D9907BF374D93E943708C91E" xlink:to="lab_us-gaap_NetCashProvidedByUsedInOperatingActivitiesAbstract_9F686BF5D9907BF374D93E943708C91E" xlink:type="arc"/>
<link:label id="lab_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_3C0B001DE02C87B9F4D83E9437081BB1_terseLabel_en-US" xlink:label="lab_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_3C0B001DE02C87B9F4D83E9437081BB1" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Adjustments to reconcile net income to net cash provided by operating activities: </link:label>
<link:label id="lab_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_3C0B001DE02C87B9F4D83E9437081BB1_label_en-US" xlink:label="lab_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_3C0B001DE02C87B9F4D83E9437081BB1" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Adjustments to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities [Abstract] </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract" xlink:label="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_3C0B001DE02C87B9F4D83E9437081BB1" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_3C0B001DE02C87B9F4D83E9437081BB1" xlink:to="lab_us-gaap_AdjustmentsToReconcileNetIncomeLossToCashProvidedByUsedInOperatingActivitiesAbstract_3C0B001DE02C87B9F4D83E9437081BB1" xlink:type="arc"/>
<link:label id="lab_us-gaap_DepreciationAndAmortization_E931CD955ABD4BBA68EB3E94370865F2_terseLabel_en-US" xlink:label="lab_us-gaap_DepreciationAndAmortization_E931CD955ABD4BBA68EB3E94370865F2" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Depreciation and amortization of intangibles </link:label>
<link:label id="lab_us-gaap_DepreciationAndAmortization_E931CD955ABD4BBA68EB3E94370865F2_label_en-US" xlink:label="lab_us-gaap_DepreciationAndAmortization_E931CD955ABD4BBA68EB3E94370865F2" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Depreciation, Depletion and Amortization, Nonproduction </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_DepreciationAndAmortization" xlink:label="loc_us-gaap_DepreciationAndAmortization_E931CD955ABD4BBA68EB3E94370865F2" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DepreciationAndAmortization_E931CD955ABD4BBA68EB3E94370865F2" xlink:to="lab_us-gaap_DepreciationAndAmortization_E931CD955ABD4BBA68EB3E94370865F2" xlink:type="arc"/>
<link:label id="lab_us-gaap_ExcessTaxBenefitFromShareBasedCompensationOperatingActivities_B0B7FD7B20BDFA39D7FC3E943708AEA1_negatedTerseLabel_en-US" xlink:label="lab_us-gaap_ExcessTaxBenefitFromShareBasedCompensationOperatingActivities_B0B7FD7B20BDFA39D7FC3E943708AEA1" xlink:role="http://www.xbrl.org/2009/role/negatedTerseLabel" xlink:type="resource" xml:lang="en-US"> Excess tax benefits from stock-based compensation exercises </link:label>
<link:label id="lab_us-gaap_ExcessTaxBenefitFromShareBasedCompensationOperatingActivities_B0B7FD7B20BDFA39D7FC3E943708AEA1_label_en-US" xlink:label="lab_us-gaap_ExcessTaxBenefitFromShareBasedCompensationOperatingActivities_B0B7FD7B20BDFA39D7FC3E943708AEA1" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Excess Tax Benefit from Share-based Compensation, Operating Activities </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ExcessTaxBenefitFromShareBasedCompensationOperatingActivities" xlink:label="loc_us-gaap_ExcessTaxBenefitFromShareBasedCompensationOperatingActivities_B0B7FD7B20BDFA39D7FC3E943708AEA1" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ExcessTaxBenefitFromShareBasedCompensationOperatingActivities_B0B7FD7B20BDFA39D7FC3E943708AEA1" xlink:to="lab_us-gaap_ExcessTaxBenefitFromShareBasedCompensationOperatingActivities_B0B7FD7B20BDFA39D7FC3E943708AEA1" xlink:type="arc"/>
<link:label id="lab_us-gaap_DeferredIncomeTaxesAndTaxCredits_3CFC71D5261F16C115173E9437080B57_terseLabel_en-US" xlink:label="lab_us-gaap_DeferredIncomeTaxesAndTaxCredits_3CFC71D5261F16C115173E9437080B57" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Deferred taxes </link:label>
<link:label id="lab_us-gaap_DeferredIncomeTaxesAndTaxCredits_3CFC71D5261F16C115173E9437080B57_label_en-US" xlink:label="lab_us-gaap_DeferredIncomeTaxesAndTaxCredits_3CFC71D5261F16C115173E9437080B57" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Deferred Income Taxes and Tax Credits </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_DeferredIncomeTaxesAndTaxCredits" xlink:label="loc_us-gaap_DeferredIncomeTaxesAndTaxCredits_3CFC71D5261F16C115173E9437080B57" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DeferredIncomeTaxesAndTaxCredits_3CFC71D5261F16C115173E9437080B57" xlink:to="lab_us-gaap_DeferredIncomeTaxesAndTaxCredits_3CFC71D5261F16C115173E9437080B57" xlink:type="arc"/>
<link:label id="lab_us-gaap_GainsLossesOnExtinguishmentOfDebt_649B76ABF95EC523C7A43EA0060E6605_negatedTerseLabel_en-US" xlink:label="lab_us-gaap_GainsLossesOnExtinguishmentOfDebt_649B76ABF95EC523C7A43EA0060E6605" xlink:role="http://www.xbrl.org/2009/role/negatedTerseLabel" xlink:type="resource" xml:lang="en-US"> Gain on extinguishment of debt </link:label>
<link:label id="lab_us-gaap_GainsLossesOnExtinguishmentOfDebt_649B76ABF95EC523C7A43EA0060E6605_label_en-US" xlink:label="lab_us-gaap_GainsLossesOnExtinguishmentOfDebt_649B76ABF95EC523C7A43EA0060E6605" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Gain (Loss) on Extinguishment of Debt </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_GainsLossesOnExtinguishmentOfDebt" xlink:label="loc_us-gaap_GainsLossesOnExtinguishmentOfDebt_649B76ABF95EC523C7A43EA0060E6605" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_GainsLossesOnExtinguishmentOfDebt_649B76ABF95EC523C7A43EA0060E6605" xlink:to="lab_us-gaap_GainsLossesOnExtinguishmentOfDebt_649B76ABF95EC523C7A43EA0060E6605" xlink:type="arc"/>
<link:label id="lab_us-gaap_AmortizationOfFinancingCosts_1111043E60CF662DD7C93E943708ADB4_terseLabel_en-US" xlink:label="lab_us-gaap_AmortizationOfFinancingCosts_1111043E60CF662DD7C93E943708ADB4" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Amortization and write-off of debt issue costs </link:label>
<link:label id="lab_us-gaap_AmortizationOfFinancingCosts_1111043E60CF662DD7C93E943708ADB4_label_en-US" xlink:label="lab_us-gaap_AmortizationOfFinancingCosts_1111043E60CF662DD7C93E943708ADB4" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Amortization of Debt Issuance Costs </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_AmortizationOfFinancingCosts" xlink:label="loc_us-gaap_AmortizationOfFinancingCosts_1111043E60CF662DD7C93E943708ADB4" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_AmortizationOfFinancingCosts_1111043E60CF662DD7C93E943708ADB4" xlink:to="lab_us-gaap_AmortizationOfFinancingCosts_1111043E60CF662DD7C93E943708ADB4" xlink:type="arc"/>
<link:label id="lab_it_ChangesInAssetsAndLiabilitiesAbstract_E83FF3C3A41AE41DA6F73E9437081BAF_terseLabel_en-US" xlink:label="lab_it_ChangesInAssetsAndLiabilitiesAbstract_E83FF3C3A41AE41DA6F73E9437081BAF" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Changes in assets and liabilities: </link:label>
<link:label id="lab_it_ChangesInAssetsAndLiabilitiesAbstract_E83FF3C3A41AE41DA6F73E9437081BAF_label_en-US" xlink:label="lab_it_ChangesInAssetsAndLiabilitiesAbstract_E83FF3C3A41AE41DA6F73E9437081BAF" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Changes in assets and liabilities: [Abstract] </link:label>
<link:label id="lab_it_ChangesInAssetsAndLiabilitiesAbstract_E83FF3C3A41AE41DA6F73E9437081BAF_documentation_en-US" xlink:label="lab_it_ChangesInAssetsAndLiabilitiesAbstract_E83FF3C3A41AE41DA6F73E9437081BAF" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US"> -- None. No documentation exists for this element. -- </link:label>
<link:loc xlink:href="it-20161231.xsd#it_ChangesInAssetsAndLiabilitiesAbstract" xlink:label="loc_it_ChangesInAssetsAndLiabilitiesAbstract_E83FF3C3A41AE41DA6F73E9437081BAF" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_it_ChangesInAssetsAndLiabilitiesAbstract_E83FF3C3A41AE41DA6F73E9437081BAF" xlink:to="lab_it_ChangesInAssetsAndLiabilitiesAbstract_E83FF3C3A41AE41DA6F73E9437081BAF" xlink:type="arc"/>
<link:label id="lab_us-gaap_IncreaseDecreaseInAccountsReceivable_FFBA965C3F8F7238CA453E943708E43B_negatedTerseLabel_en-US" xlink:label="lab_us-gaap_IncreaseDecreaseInAccountsReceivable_FFBA965C3F8F7238CA453E943708E43B" xlink:role="http://www.xbrl.org/2009/role/negatedTerseLabel" xlink:type="resource" xml:lang="en-US"> Fees receivable, net </link:label>
<link:label id="lab_us-gaap_IncreaseDecreaseInAccountsReceivable_FFBA965C3F8F7238CA453E943708E43B_label_en-US" xlink:label="lab_us-gaap_IncreaseDecreaseInAccountsReceivable_FFBA965C3F8F7238CA453E943708E43B" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Increase (Decrease) in Accounts Receivable </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_IncreaseDecreaseInAccountsReceivable" xlink:label="loc_us-gaap_IncreaseDecreaseInAccountsReceivable_FFBA965C3F8F7238CA453E943708E43B" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_IncreaseDecreaseInAccountsReceivable_FFBA965C3F8F7238CA453E943708E43B" xlink:to="lab_us-gaap_IncreaseDecreaseInAccountsReceivable_FFBA965C3F8F7238CA453E943708E43B" xlink:type="arc"/>
<link:label id="lab_us-gaap_IncreaseDecreaseInDeferredCharges_47CA65F873FB9C8684FE3E9437084A0C_negatedTerseLabel_en-US" xlink:label="lab_us-gaap_IncreaseDecreaseInDeferredCharges_47CA65F873FB9C8684FE3E9437084A0C" xlink:role="http://www.xbrl.org/2009/role/negatedTerseLabel" xlink:type="resource" xml:lang="en-US"> Deferred commissions </link:label>
<link:label id="lab_us-gaap_IncreaseDecreaseInDeferredCharges_47CA65F873FB9C8684FE3E9437084A0C_label_en-US" xlink:label="lab_us-gaap_IncreaseDecreaseInDeferredCharges_47CA65F873FB9C8684FE3E9437084A0C" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Increase (Decrease) in Deferred Charges </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_IncreaseDecreaseInDeferredCharges" xlink:label="loc_us-gaap_IncreaseDecreaseInDeferredCharges_47CA65F873FB9C8684FE3E9437084A0C" xlink:type="locator"/>
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<link:label id="lab_us-gaap_IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets_F91EDC063300425F36E53E9437086528_negatedTerseLabel_en-US" xlink:label="lab_us-gaap_IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets_F91EDC063300425F36E53E9437086528" xlink:role="http://www.xbrl.org/2009/role/negatedTerseLabel" xlink:type="resource" xml:lang="en-US"> Prepaid expenses and other current assets </link:label>
<link:label id="lab_us-gaap_IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets_F91EDC063300425F36E53E9437086528_label_en-US" xlink:label="lab_us-gaap_IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets_F91EDC063300425F36E53E9437086528" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Increase (Decrease) in Prepaid Expense and Other Assets </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets" xlink:label="loc_us-gaap_IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets_F91EDC063300425F36E53E9437086528" xlink:type="locator"/>
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<link:label id="lab_us-gaap_IncreaseDecreaseInOtherOperatingAssets_26C03D9174F16522910C3E9437083B98_negatedTerseLabel_en-US" xlink:label="lab_us-gaap_IncreaseDecreaseInOtherOperatingAssets_26C03D9174F16522910C3E9437083B98" xlink:role="http://www.xbrl.org/2009/role/negatedTerseLabel" xlink:type="resource" xml:lang="en-US"> Other assets </link:label>
<link:label id="lab_us-gaap_IncreaseDecreaseInOtherOperatingAssets_26C03D9174F16522910C3E9437083B98_label_en-US" xlink:label="lab_us-gaap_IncreaseDecreaseInOtherOperatingAssets_26C03D9174F16522910C3E9437083B98" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Increase (Decrease) in Other Operating Assets </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_IncreaseDecreaseInOtherOperatingAssets" xlink:label="loc_us-gaap_IncreaseDecreaseInOtherOperatingAssets_26C03D9174F16522910C3E9437083B98" xlink:type="locator"/>
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<link:label id="lab_us-gaap_IncreaseDecreaseInDeferredRevenue_EA613088297CA95EB18C3E9437089636_terseLabel_en-US" xlink:label="lab_us-gaap_IncreaseDecreaseInDeferredRevenue_EA613088297CA95EB18C3E9437089636" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Deferred revenues </link:label>
<link:label id="lab_us-gaap_IncreaseDecreaseInDeferredRevenue_EA613088297CA95EB18C3E9437089636_label_en-US" xlink:label="lab_us-gaap_IncreaseDecreaseInDeferredRevenue_EA613088297CA95EB18C3E9437089636" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Increase (Decrease) in Deferred Revenue </link:label>
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<link:label id="lab_us-gaap_IncreaseDecreaseInAccountsPayableAndAccruedLiabilities_32211115DD574AD55ECC3E9437095000_terseLabel_en-US" xlink:label="lab_us-gaap_IncreaseDecreaseInAccountsPayableAndAccruedLiabilities_32211115DD574AD55ECC3E9437095000" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Accounts payable, accrued, and other liabilities </link:label>
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<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_IncreaseDecreaseInAccountsPayableAndAccruedLiabilities" xlink:label="loc_us-gaap_IncreaseDecreaseInAccountsPayableAndAccruedLiabilities_32211115DD574AD55ECC3E9437095000" xlink:type="locator"/>
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<link:label id="lab_us-gaap_NetCashProvidedByUsedInOperatingActivities_324DAB298653144642FD3E943709CF70_totalLabel_en-US" xlink:label="lab_us-gaap_NetCashProvidedByUsedInOperatingActivities_324DAB298653144642FD3E943709CF70" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:type="resource" xml:lang="en-US"> Cash provided by operating activities </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_NetCashProvidedByUsedInOperatingActivities" xlink:label="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_324DAB298653144642FD3E943709CF70" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_NetCashProvidedByUsedInOperatingActivities_324DAB298653144642FD3E943709CF70" xlink:to="lab_us-gaap_NetCashProvidedByUsedInOperatingActivities_324DAB298653144642FD3E943709CF70" xlink:type="arc"/>
<link:label id="lab_us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract_A3A87DC4ABA25DBF381F3E94370961B6_terseLabel_en-US" xlink:label="lab_us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract_A3A87DC4ABA25DBF381F3E94370961B6" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Investing activities: </link:label>
<link:label id="lab_us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract_A3A87DC4ABA25DBF381F3E94370961B6_label_en-US" xlink:label="lab_us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract_A3A87DC4ABA25DBF381F3E94370961B6" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Net Cash Provided by (Used in) Investing Activities [Abstract] </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract" xlink:label="loc_us-gaap_NetCashProvidedByUsedInInvestingActivitiesAbstract_A3A87DC4ABA25DBF381F3E94370961B6" xlink:type="locator"/>
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<link:label id="lab_us-gaap_PaymentsForCapitalImprovements_B4F9FEE9EF18372D786A3E94370979E6_negatedLabel_en-US" xlink:label="lab_us-gaap_PaymentsForCapitalImprovements_B4F9FEE9EF18372D786A3E94370979E6" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:type="resource" xml:lang="en-US"> Additions to property, equipment and leasehold improvements </link:label>
<link:label id="lab_us-gaap_PaymentsForCapitalImprovements_B4F9FEE9EF18372D786A3E94370979E6_label_en-US" xlink:label="lab_us-gaap_PaymentsForCapitalImprovements_B4F9FEE9EF18372D786A3E94370979E6" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Payments for Capital Improvements </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_PaymentsForCapitalImprovements" xlink:label="loc_us-gaap_PaymentsForCapitalImprovements_B4F9FEE9EF18372D786A3E94370979E6" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_PaymentsForCapitalImprovements_B4F9FEE9EF18372D786A3E94370979E6" xlink:to="lab_us-gaap_PaymentsForCapitalImprovements_B4F9FEE9EF18372D786A3E94370979E6" xlink:type="arc"/>
<link:label id="lab_us-gaap_PaymentsToAcquireBusinessesNetOfCashAcquired_7DECE1D1104FF92F0ECD3E943709F921_negatedLabel_en-US" xlink:label="lab_us-gaap_PaymentsToAcquireBusinessesNetOfCashAcquired_7DECE1D1104FF92F0ECD3E943709F921" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:type="resource" xml:lang="en-US"> Acquisitions (net of cash acquired) </link:label>
<link:label id="lab_us-gaap_PaymentsToAcquireBusinessesNetOfCashAcquired_7DECE1D1104FF92F0ECD3E943709F921_label_en-US" xlink:label="lab_us-gaap_PaymentsToAcquireBusinessesNetOfCashAcquired_7DECE1D1104FF92F0ECD3E943709F921" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Payments to Acquire Businesses, Net of Cash Acquired </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_PaymentsToAcquireBusinessesNetOfCashAcquired" xlink:label="loc_us-gaap_PaymentsToAcquireBusinessesNetOfCashAcquired_7DECE1D1104FF92F0ECD3E943709F921" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_PaymentsToAcquireBusinessesNetOfCashAcquired_7DECE1D1104FF92F0ECD3E943709F921" xlink:to="lab_us-gaap_PaymentsToAcquireBusinessesNetOfCashAcquired_7DECE1D1104FF92F0ECD3E943709F921" xlink:type="arc"/>
<link:label id="lab_us-gaap_NetCashProvidedByUsedInInvestingActivities_033A0ADEAA51D5BB442E3E94370971E3_totalLabel_en-US" xlink:label="lab_us-gaap_NetCashProvidedByUsedInInvestingActivities_033A0ADEAA51D5BB442E3E94370971E3" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:type="resource" xml:lang="en-US"> Cash used in investing activities </link:label>
<link:label id="lab_us-gaap_NetCashProvidedByUsedInInvestingActivities_033A0ADEAA51D5BB442E3E94370971E3_label_en-US" xlink:label="lab_us-gaap_NetCashProvidedByUsedInInvestingActivities_033A0ADEAA51D5BB442E3E94370971E3" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Net Cash Provided by (Used in) Investing Activities </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_NetCashProvidedByUsedInInvestingActivities" xlink:label="loc_us-gaap_NetCashProvidedByUsedInInvestingActivities_033A0ADEAA51D5BB442E3E94370971E3" xlink:type="locator"/>
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<link:label id="lab_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_29638C20393BD07777463E943709ED5D_terseLabel_en-US" xlink:label="lab_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_29638C20393BD07777463E943709ED5D" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Financing activities: </link:label>
<link:label id="lab_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_29638C20393BD07777463E943709ED5D_label_en-US" xlink:label="lab_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_29638C20393BD07777463E943709ED5D" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Net Cash Provided by (Used in) Financing Activities [Abstract] </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract" xlink:label="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_29638C20393BD07777463E943709ED5D" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_29638C20393BD07777463E943709ED5D" xlink:to="lab_us-gaap_NetCashProvidedByUsedInFinancingActivitiesAbstract_29638C20393BD07777463E943709ED5D" xlink:type="arc"/>
<link:label id="lab_us-gaap_ProceedsFromIssuanceOfSharesUnderIncentiveAndShareBasedCompensationPlansIncludingStockOptions_A730C7D282F94DD0B32B3E943709E6E0_terseLabel_en-US" xlink:label="lab_us-gaap_ProceedsFromIssuanceOfSharesUnderIncentiveAndShareBasedCompensationPlansIncludingStockOptions_A730C7D282F94DD0B32B3E943709E6E0" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Proceeds from ESP Plan </link:label>
<link:label id="lab_us-gaap_ProceedsFromIssuanceOfSharesUnderIncentiveAndShareBasedCompensationPlansIncludingStockOptions_A730C7D282F94DD0B32B3E943709E6E0_label_en-US" xlink:label="lab_us-gaap_ProceedsFromIssuanceOfSharesUnderIncentiveAndShareBasedCompensationPlansIncludingStockOptions_A730C7D282F94DD0B32B3E943709E6E0" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Proceeds from Issuance of Shares under Incentive and Share-based Compensation Plans, Including Stock Options </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ProceedsFromIssuanceOfSharesUnderIncentiveAndShareBasedCompensationPlansIncludingStockOptions" xlink:label="loc_us-gaap_ProceedsFromIssuanceOfSharesUnderIncentiveAndShareBasedCompensationPlansIncludingStockOptions_A730C7D282F94DD0B32B3E943709E6E0" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ProceedsFromIssuanceOfSharesUnderIncentiveAndShareBasedCompensationPlansIncludingStockOptions_A730C7D282F94DD0B32B3E943709E6E0" xlink:to="lab_us-gaap_ProceedsFromIssuanceOfSharesUnderIncentiveAndShareBasedCompensationPlansIncludingStockOptions_A730C7D282F94DD0B32B3E943709E6E0" xlink:type="arc"/>
<link:label id="lab_us-gaap_ProceedsFromIssuanceOfLongTermDebt_ABF38EE4D9E40B2BB7403E9437098530_terseLabel_en-US" xlink:label="lab_us-gaap_ProceedsFromIssuanceOfLongTermDebt_ABF38EE4D9E40B2BB7403E9437098530" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Proceeds from borrowings </link:label>
<link:label id="lab_us-gaap_ProceedsFromIssuanceOfLongTermDebt_ABF38EE4D9E40B2BB7403E9437098530_label_en-US" xlink:label="lab_us-gaap_ProceedsFromIssuanceOfLongTermDebt_ABF38EE4D9E40B2BB7403E9437098530" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Proceeds from Issuance of Long-term Debt </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ProceedsFromIssuanceOfLongTermDebt" xlink:label="loc_us-gaap_ProceedsFromIssuanceOfLongTermDebt_ABF38EE4D9E40B2BB7403E9437098530" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ProceedsFromIssuanceOfLongTermDebt_ABF38EE4D9E40B2BB7403E9437098530" xlink:to="lab_us-gaap_ProceedsFromIssuanceOfLongTermDebt_ABF38EE4D9E40B2BB7403E9437098530" xlink:type="arc"/>
<link:label id="lab_us-gaap_RepaymentsOfLongTermDebt_6E8C4AC22D6A50D1D7EC3E943709E84B_negatedLabel_en-US" xlink:label="lab_us-gaap_RepaymentsOfLongTermDebt_6E8C4AC22D6A50D1D7EC3E943709E84B" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:type="resource" xml:lang="en-US"> Payments on debt </link:label>
<link:label id="lab_us-gaap_RepaymentsOfLongTermDebt_6E8C4AC22D6A50D1D7EC3E943709E84B_label_en-US" xlink:label="lab_us-gaap_RepaymentsOfLongTermDebt_6E8C4AC22D6A50D1D7EC3E943709E84B" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Repayments of Long-term Debt </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_RepaymentsOfLongTermDebt" xlink:label="loc_us-gaap_RepaymentsOfLongTermDebt_6E8C4AC22D6A50D1D7EC3E943709E84B" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_RepaymentsOfLongTermDebt_6E8C4AC22D6A50D1D7EC3E943709E84B" xlink:to="lab_us-gaap_RepaymentsOfLongTermDebt_6E8C4AC22D6A50D1D7EC3E943709E84B" xlink:type="arc"/>
<link:label id="lab_us-gaap_PaymentsForRepurchaseOfCommonStock_371801C48137075A3F573E9437092171_negatedLabel_en-US" xlink:label="lab_us-gaap_PaymentsForRepurchaseOfCommonStock_371801C48137075A3F573E9437092171" xlink:role="http://www.xbrl.org/2009/role/negatedLabel" xlink:type="resource" xml:lang="en-US"> Purchases of treasury stock </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_PaymentsForRepurchaseOfCommonStock" xlink:label="loc_us-gaap_PaymentsForRepurchaseOfCommonStock_371801C48137075A3F573E9437092171" xlink:type="locator"/>
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<link:label id="lab_us-gaap_PaymentsOfDebtIssuanceCosts_CB02FEEDEF680ECE92133E943709C95A_negatedTerseLabel_en-US" xlink:label="lab_us-gaap_PaymentsOfDebtIssuanceCosts_CB02FEEDEF680ECE92133E943709C95A" xlink:role="http://www.xbrl.org/2009/role/negatedTerseLabel" xlink:type="resource" xml:lang="en-US"> Fees paid for debt refinancing </link:label>
<link:label id="lab_us-gaap_PaymentsOfDebtIssuanceCosts_CB02FEEDEF680ECE92133E943709C95A_label_en-US" xlink:label="lab_us-gaap_PaymentsOfDebtIssuanceCosts_CB02FEEDEF680ECE92133E943709C95A" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Payments of Debt Issuance Costs </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_PaymentsOfDebtIssuanceCosts" xlink:label="loc_us-gaap_PaymentsOfDebtIssuanceCosts_CB02FEEDEF680ECE92133E943709C95A" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_PaymentsOfDebtIssuanceCosts_CB02FEEDEF680ECE92133E943709C95A" xlink:to="lab_us-gaap_PaymentsOfDebtIssuanceCosts_CB02FEEDEF680ECE92133E943709C95A" xlink:type="arc"/>
<link:label id="lab_us-gaap_ExcessTaxBenefitFromShareBasedCompensationFinancingActivities_C14A9A1D5E249A83CF6F3E9437094D19_terseLabel_en-US" xlink:label="lab_us-gaap_ExcessTaxBenefitFromShareBasedCompensationFinancingActivities_C14A9A1D5E249A83CF6F3E9437094D19" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Excess tax benefits from stock-based compensation exercises </link:label>
<link:label id="lab_us-gaap_ExcessTaxBenefitFromShareBasedCompensationFinancingActivities_C14A9A1D5E249A83CF6F3E9437094D19_label_en-US" xlink:label="lab_us-gaap_ExcessTaxBenefitFromShareBasedCompensationFinancingActivities_C14A9A1D5E249A83CF6F3E9437094D19" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Excess Tax Benefit from Share-based Compensation, Financing Activities </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ExcessTaxBenefitFromShareBasedCompensationFinancingActivities" xlink:label="loc_us-gaap_ExcessTaxBenefitFromShareBasedCompensationFinancingActivities_C14A9A1D5E249A83CF6F3E9437094D19" xlink:type="locator"/>
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<link:label id="lab_us-gaap_NetCashProvidedByUsedInFinancingActivities_20C3DA7D50238FD45BA43E943709ED87_totalLabel_en-US" xlink:label="lab_us-gaap_NetCashProvidedByUsedInFinancingActivities_20C3DA7D50238FD45BA43E943709ED87" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:type="resource" xml:lang="en-US"> Cash used by financing activities </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_NetCashProvidedByUsedInFinancingActivities" xlink:label="loc_us-gaap_NetCashProvidedByUsedInFinancingActivities_20C3DA7D50238FD45BA43E943709ED87" xlink:type="locator"/>
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<link:label id="lab_us-gaap_CashAndCashEquivalentsPeriodIncreaseDecreaseExcludingExchangeRateEffect_D93C657E4768F49E9A7C3E94370954FA_totalLabel_en-US" xlink:label="lab_us-gaap_CashAndCashEquivalentsPeriodIncreaseDecreaseExcludingExchangeRateEffect_D93C657E4768F49E9A7C3E94370954FA" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:type="resource" xml:lang="en-US"> Net increase (decrease) in cash and cash equivalents </link:label>
<link:label id="lab_us-gaap_CashAndCashEquivalentsPeriodIncreaseDecreaseExcludingExchangeRateEffect_D93C657E4768F49E9A7C3E94370954FA_label_en-US" xlink:label="lab_us-gaap_CashAndCashEquivalentsPeriodIncreaseDecreaseExcludingExchangeRateEffect_D93C657E4768F49E9A7C3E94370954FA" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Cash and Cash Equivalents, Period Increase (Decrease), Excluding Exchange Rate Effect </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_CashAndCashEquivalentsPeriodIncreaseDecreaseExcludingExchangeRateEffect" xlink:label="loc_us-gaap_CashAndCashEquivalentsPeriodIncreaseDecreaseExcludingExchangeRateEffect_D93C657E4768F49E9A7C3E94370954FA" xlink:type="locator"/>
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<link:label id="lab_us-gaap_EffectOfExchangeRateOnCashAndCashEquivalents_A9804515368194562B093E943709F1EA_terseLabel_en-US" xlink:label="lab_us-gaap_EffectOfExchangeRateOnCashAndCashEquivalents_A9804515368194562B093E943709F1EA" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Effects of exchange rates on cash and cash equivalents </link:label>
<link:label id="lab_us-gaap_EffectOfExchangeRateOnCashAndCashEquivalents_A9804515368194562B093E943709F1EA_label_en-US" xlink:label="lab_us-gaap_EffectOfExchangeRateOnCashAndCashEquivalents_A9804515368194562B093E943709F1EA" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Effect of Exchange Rate on Cash and Cash Equivalents </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_EffectOfExchangeRateOnCashAndCashEquivalents" xlink:label="loc_us-gaap_EffectOfExchangeRateOnCashAndCashEquivalents_A9804515368194562B093E943709F1EA" xlink:type="locator"/>
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<link:label id="lab_us-gaap_CashAndCashEquivalentsAtCarryingValue_8010FDEE775DAA5608C13E94370996E0_periodStartLabel_en-US" xlink:label="lab_us-gaap_CashAndCashEquivalentsAtCarryingValue_8010FDEE775DAA5608C13E94370996E0" xlink:role="http://www.xbrl.org/2003/role/periodStartLabel" xlink:type="resource" xml:lang="en-US"> Cash and cash equivalents, beginning of period </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_CashAndCashEquivalentsAtCarryingValue" xlink:label="loc_us-gaap_CashAndCashEquivalentsAtCarryingValue_8010FDEE775DAA5608C13E94370996E0" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_CashAndCashEquivalentsAtCarryingValue_8010FDEE775DAA5608C13E94370996E0" xlink:to="lab_us-gaap_CashAndCashEquivalentsAtCarryingValue_8010FDEE775DAA5608C13E94370996E0" xlink:type="arc"/>
<link:label id="lab_us-gaap_CashAndCashEquivalentsAtCarryingValue_52956D1552F93F93FB2C3E943709E0AC_periodEndLabel_en-US" xlink:label="lab_us-gaap_CashAndCashEquivalentsAtCarryingValue_52956D1552F93F93FB2C3E943709E0AC" xlink:role="http://www.xbrl.org/2003/role/periodEndLabel" xlink:type="resource" xml:lang="en-US"> Cash and cash equivalents, end of period </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_CashAndCashEquivalentsAtCarryingValue" xlink:label="loc_us-gaap_CashAndCashEquivalentsAtCarryingValue_52956D1552F93F93FB2C3E943709E0AC" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_CashAndCashEquivalentsAtCarryingValue_52956D1552F93F93FB2C3E943709E0AC" xlink:to="lab_us-gaap_CashAndCashEquivalentsAtCarryingValue_52956D1552F93F93FB2C3E943709E0AC" xlink:type="arc"/>
<link:label id="lab_us-gaap_SupplementalCashFlowInformationAbstract_2D4D78E39B881F2E76E03E94370A0F40_terseLabel_en-US" xlink:label="lab_us-gaap_SupplementalCashFlowInformationAbstract_2D4D78E39B881F2E76E03E94370A0F40" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Supplemental disclosures of cash flow information: </link:label>
<link:label id="lab_us-gaap_SupplementalCashFlowInformationAbstract_2D4D78E39B881F2E76E03E94370A0F40_label_en-US" xlink:label="lab_us-gaap_SupplementalCashFlowInformationAbstract_2D4D78E39B881F2E76E03E94370A0F40" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Supplemental Cash Flow Information [Abstract] </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_SupplementalCashFlowInformationAbstract" xlink:label="loc_us-gaap_SupplementalCashFlowInformationAbstract_2D4D78E39B881F2E76E03E94370A0F40" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_SupplementalCashFlowInformationAbstract_2D4D78E39B881F2E76E03E94370A0F40" xlink:to="lab_us-gaap_SupplementalCashFlowInformationAbstract_2D4D78E39B881F2E76E03E94370A0F40" xlink:type="arc"/>
<link:label id="lab_it_CashPaidDuringThePeriodForAbstract_4AEAB3EE94D26CDC2B933E94370A8E1C_terseLabel_en-US" xlink:label="lab_it_CashPaidDuringThePeriodForAbstract_4AEAB3EE94D26CDC2B933E94370A8E1C" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Cash paid during the period for: </link:label>
<link:label id="lab_it_CashPaidDuringThePeriodForAbstract_4AEAB3EE94D26CDC2B933E94370A8E1C_label_en-US" xlink:label="lab_it_CashPaidDuringThePeriodForAbstract_4AEAB3EE94D26CDC2B933E94370A8E1C" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Cash paid during the period for: [Abstract] </link:label>
<link:label id="lab_it_CashPaidDuringThePeriodForAbstract_4AEAB3EE94D26CDC2B933E94370A8E1C_documentation_en-US" xlink:label="lab_it_CashPaidDuringThePeriodForAbstract_4AEAB3EE94D26CDC2B933E94370A8E1C" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US"> -- None. No documentation exists for this element. -- </link:label>
<link:loc xlink:href="it-20161231.xsd#it_CashPaidDuringThePeriodForAbstract" xlink:label="loc_it_CashPaidDuringThePeriodForAbstract_4AEAB3EE94D26CDC2B933E94370A8E1C" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_it_CashPaidDuringThePeriodForAbstract_4AEAB3EE94D26CDC2B933E94370A8E1C" xlink:to="lab_it_CashPaidDuringThePeriodForAbstract_4AEAB3EE94D26CDC2B933E94370A8E1C" xlink:type="arc"/>
<link:label id="lab_us-gaap_InterestPaid_1C8BD4FD55E221A291133E94370AD3C0_terseLabel_en-US" xlink:label="lab_us-gaap_InterestPaid_1C8BD4FD55E221A291133E94370AD3C0" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Interest </link:label>
<link:label id="lab_us-gaap_InterestPaid_1C8BD4FD55E221A291133E94370AD3C0_label_en-US" xlink:label="lab_us-gaap_InterestPaid_1C8BD4FD55E221A291133E94370AD3C0" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Interest Paid </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_InterestPaid" xlink:label="loc_us-gaap_InterestPaid_1C8BD4FD55E221A291133E94370AD3C0" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_InterestPaid_1C8BD4FD55E221A291133E94370AD3C0" xlink:to="lab_us-gaap_InterestPaid_1C8BD4FD55E221A291133E94370AD3C0" xlink:type="arc"/>
<link:label id="lab_us-gaap_IncomeTaxesPaidNet_5490261EC3D6D55F58BC3E94370AB098_terseLabel_en-US" xlink:label="lab_us-gaap_IncomeTaxesPaidNet_5490261EC3D6D55F58BC3E94370AB098" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Income taxes, net of refunds received </link:label>
<link:label id="lab_us-gaap_IncomeTaxesPaidNet_5490261EC3D6D55F58BC3E94370AB098_label_en-US" xlink:label="lab_us-gaap_IncomeTaxesPaidNet_5490261EC3D6D55F58BC3E94370AB098" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Income Taxes Paid, Net </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_IncomeTaxesPaidNet" xlink:label="loc_us-gaap_IncomeTaxesPaidNet_5490261EC3D6D55F58BC3E94370AB098" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_IncomeTaxesPaidNet_5490261EC3D6D55F58BC3E94370AB098" xlink:to="lab_us-gaap_IncomeTaxesPaidNet_5490261EC3D6D55F58BC3E94370AB098" xlink:type="arc"/>
<link:label id="lab_us-gaap_CommitmentsAndContingenciesDisclosureAbstract_C6EA839E1B5A8FCDE778B33DF71462E1_label_en-US" xlink:label="lab_us-gaap_CommitmentsAndContingenciesDisclosureAbstract_C6EA839E1B5A8FCDE778B33DF71462E1" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Commitments and Contingencies Disclosure [Abstract] </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_CommitmentsAndContingenciesDisclosureAbstract" xlink:label="loc_us-gaap_CommitmentsAndContingenciesDisclosureAbstract_C6EA839E1B5A8FCDE778B33DF71462E1" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_CommitmentsAndContingenciesDisclosureAbstract_C6EA839E1B5A8FCDE778B33DF71462E1" xlink:to="lab_us-gaap_CommitmentsAndContingenciesDisclosureAbstract_C6EA839E1B5A8FCDE778B33DF71462E1" xlink:type="arc"/>
<link:label id="lab_us-gaap_OperatingLeasesFutureMinimumPaymentsDueAbstract_5816EAD9F53747F39912B33DF714F127_terseLabel_en-US" xlink:label="lab_us-gaap_OperatingLeasesFutureMinimumPaymentsDueAbstract_5816EAD9F53747F39912B33DF714F127" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract] </link:label>
<link:label id="lab_us-gaap_OperatingLeasesFutureMinimumPaymentsDueAbstract_5816EAD9F53747F39912B33DF714F127_label_en-US" xlink:label="lab_us-gaap_OperatingLeasesFutureMinimumPaymentsDueAbstract_5816EAD9F53747F39912B33DF714F127" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract] </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_OperatingLeasesFutureMinimumPaymentsDueAbstract" xlink:label="loc_us-gaap_OperatingLeasesFutureMinimumPaymentsDueAbstract_5816EAD9F53747F39912B33DF714F127" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_OperatingLeasesFutureMinimumPaymentsDueAbstract_5816EAD9F53747F39912B33DF714F127" xlink:to="lab_us-gaap_OperatingLeasesFutureMinimumPaymentsDueAbstract_5816EAD9F53747F39912B33DF714F127" xlink:type="arc"/>
<link:label id="lab_us-gaap_OperatingLeasesFutureMinimumPaymentsDueCurrent_7F8276FA4270D588DB09B33DF7159F60_terseLabel_en-US" xlink:label="lab_us-gaap_OperatingLeasesFutureMinimumPaymentsDueCurrent_7F8276FA4270D588DB09B33DF7159F60" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> 2017 </link:label>
<link:label id="lab_us-gaap_OperatingLeasesFutureMinimumPaymentsDueCurrent_7F8276FA4270D588DB09B33DF7159F60_label_en-US" xlink:label="lab_us-gaap_OperatingLeasesFutureMinimumPaymentsDueCurrent_7F8276FA4270D588DB09B33DF7159F60" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Operating Leases, Future Minimum Payments Due, Next Twelve Months </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_OperatingLeasesFutureMinimumPaymentsDueCurrent" xlink:label="loc_us-gaap_OperatingLeasesFutureMinimumPaymentsDueCurrent_7F8276FA4270D588DB09B33DF7159F60" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_OperatingLeasesFutureMinimumPaymentsDueCurrent_7F8276FA4270D588DB09B33DF7159F60" xlink:to="lab_us-gaap_OperatingLeasesFutureMinimumPaymentsDueCurrent_7F8276FA4270D588DB09B33DF7159F60" xlink:type="arc"/>
<link:label id="lab_us-gaap_OperatingLeasesFutureMinimumPaymentsDueInTwoYears_D32A0518482DB78344B0B33DF715B607_terseLabel_en-US" xlink:label="lab_us-gaap_OperatingLeasesFutureMinimumPaymentsDueInTwoYears_D32A0518482DB78344B0B33DF715B607" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> 2018 </link:label>
<link:label id="lab_us-gaap_OperatingLeasesFutureMinimumPaymentsDueInTwoYears_D32A0518482DB78344B0B33DF715B607_label_en-US" xlink:label="lab_us-gaap_OperatingLeasesFutureMinimumPaymentsDueInTwoYears_D32A0518482DB78344B0B33DF715B607" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Operating Leases, Future Minimum Payments, Due in Two Years </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_OperatingLeasesFutureMinimumPaymentsDueInTwoYears" xlink:label="loc_us-gaap_OperatingLeasesFutureMinimumPaymentsDueInTwoYears_D32A0518482DB78344B0B33DF715B607" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_OperatingLeasesFutureMinimumPaymentsDueInTwoYears_D32A0518482DB78344B0B33DF715B607" xlink:to="lab_us-gaap_OperatingLeasesFutureMinimumPaymentsDueInTwoYears_D32A0518482DB78344B0B33DF715B607" xlink:type="arc"/>
<link:label id="lab_us-gaap_OperatingLeasesFutureMinimumPaymentsDueInThreeYears_934A4B747EB72FECD0E9B33DF715F841_terseLabel_en-US" xlink:label="lab_us-gaap_OperatingLeasesFutureMinimumPaymentsDueInThreeYears_934A4B747EB72FECD0E9B33DF715F841" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> 2019 </link:label>
<link:label id="lab_us-gaap_OperatingLeasesFutureMinimumPaymentsDueInThreeYears_934A4B747EB72FECD0E9B33DF715F841_label_en-US" xlink:label="lab_us-gaap_OperatingLeasesFutureMinimumPaymentsDueInThreeYears_934A4B747EB72FECD0E9B33DF715F841" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Operating Leases, Future Minimum Payments, Due in Three Years </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_OperatingLeasesFutureMinimumPaymentsDueInThreeYears" xlink:label="loc_us-gaap_OperatingLeasesFutureMinimumPaymentsDueInThreeYears_934A4B747EB72FECD0E9B33DF715F841" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_OperatingLeasesFutureMinimumPaymentsDueInThreeYears_934A4B747EB72FECD0E9B33DF715F841" xlink:to="lab_us-gaap_OperatingLeasesFutureMinimumPaymentsDueInThreeYears_934A4B747EB72FECD0E9B33DF715F841" xlink:type="arc"/>
<link:label id="lab_us-gaap_OperatingLeasesFutureMinimumPaymentsDueInFourYears_1E7BABF81F636882DB10B33DF715E680_terseLabel_en-US" xlink:label="lab_us-gaap_OperatingLeasesFutureMinimumPaymentsDueInFourYears_1E7BABF81F636882DB10B33DF715E680" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> 2020 </link:label>
<link:label id="lab_us-gaap_OperatingLeasesFutureMinimumPaymentsDueInFourYears_1E7BABF81F636882DB10B33DF715E680_label_en-US" xlink:label="lab_us-gaap_OperatingLeasesFutureMinimumPaymentsDueInFourYears_1E7BABF81F636882DB10B33DF715E680" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Operating Leases, Future Minimum Payments, Due in Four Years </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_OperatingLeasesFutureMinimumPaymentsDueInFourYears" xlink:label="loc_us-gaap_OperatingLeasesFutureMinimumPaymentsDueInFourYears_1E7BABF81F636882DB10B33DF715E680" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_OperatingLeasesFutureMinimumPaymentsDueInFourYears_1E7BABF81F636882DB10B33DF715E680" xlink:to="lab_us-gaap_OperatingLeasesFutureMinimumPaymentsDueInFourYears_1E7BABF81F636882DB10B33DF715E680" xlink:type="arc"/>
<link:label id="lab_us-gaap_OperatingLeasesFutureMinimumPaymentsDueInFiveYears_22D2863DEA61A523FAFEB33DF715F3CD_terseLabel_en-US" xlink:label="lab_us-gaap_OperatingLeasesFutureMinimumPaymentsDueInFiveYears_22D2863DEA61A523FAFEB33DF715F3CD" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> 2021 </link:label>
<link:label id="lab_us-gaap_OperatingLeasesFutureMinimumPaymentsDueInFiveYears_22D2863DEA61A523FAFEB33DF715F3CD_label_en-US" xlink:label="lab_us-gaap_OperatingLeasesFutureMinimumPaymentsDueInFiveYears_22D2863DEA61A523FAFEB33DF715F3CD" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Operating Leases, Future Minimum Payments, Due in Five Years </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_OperatingLeasesFutureMinimumPaymentsDueInFiveYears" xlink:label="loc_us-gaap_OperatingLeasesFutureMinimumPaymentsDueInFiveYears_22D2863DEA61A523FAFEB33DF715F3CD" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_OperatingLeasesFutureMinimumPaymentsDueInFiveYears_22D2863DEA61A523FAFEB33DF715F3CD" xlink:to="lab_us-gaap_OperatingLeasesFutureMinimumPaymentsDueInFiveYears_22D2863DEA61A523FAFEB33DF715F3CD" xlink:type="arc"/>
<link:label id="lab_us-gaap_OperatingLeasesFutureMinimumPaymentsDueThereafter_413C23F671C9AD090A0EB33DF715377D_terseLabel_en-US" xlink:label="lab_us-gaap_OperatingLeasesFutureMinimumPaymentsDueThereafter_413C23F671C9AD090A0EB33DF715377D" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Thereafter </link:label>
<link:label id="lab_us-gaap_OperatingLeasesFutureMinimumPaymentsDueThereafter_413C23F671C9AD090A0EB33DF715377D_label_en-US" xlink:label="lab_us-gaap_OperatingLeasesFutureMinimumPaymentsDueThereafter_413C23F671C9AD090A0EB33DF715377D" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Operating Leases, Future Minimum Payments, Due Thereafter </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_OperatingLeasesFutureMinimumPaymentsDueThereafter" xlink:label="loc_us-gaap_OperatingLeasesFutureMinimumPaymentsDueThereafter_413C23F671C9AD090A0EB33DF715377D" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_OperatingLeasesFutureMinimumPaymentsDueThereafter_413C23F671C9AD090A0EB33DF715377D" xlink:to="lab_us-gaap_OperatingLeasesFutureMinimumPaymentsDueThereafter_413C23F671C9AD090A0EB33DF715377D" xlink:type="arc"/>
<link:label id="lab_us-gaap_OperatingLeasesFutureMinimumPaymentsDue_DC1F5844A7C543E52411B33DF71721B7_totalLabel_en-US" xlink:label="lab_us-gaap_OperatingLeasesFutureMinimumPaymentsDue_DC1F5844A7C543E52411B33DF71721B7" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:type="resource" xml:lang="en-US"> Total minimum lease payments </link:label>
<link:label id="lab_us-gaap_OperatingLeasesFutureMinimumPaymentsDue_DC1F5844A7C543E52411B33DF71721B7_label_en-US" xlink:label="lab_us-gaap_OperatingLeasesFutureMinimumPaymentsDue_DC1F5844A7C543E52411B33DF71721B7" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Operating Leases, Future Minimum Payments Due </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_OperatingLeasesFutureMinimumPaymentsDue" xlink:label="loc_us-gaap_OperatingLeasesFutureMinimumPaymentsDue_DC1F5844A7C543E52411B33DF71721B7" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_OperatingLeasesFutureMinimumPaymentsDue_DC1F5844A7C543E52411B33DF71721B7" xlink:to="lab_us-gaap_OperatingLeasesFutureMinimumPaymentsDue_DC1F5844A7C543E52411B33DF71721B7" xlink:type="arc"/>
<link:label id="lab_it_NumeratorAbstract_327E159CF35F8F80ACE6997A0DE0BB52_terseLabel_en-US" xlink:label="lab_it_NumeratorAbstract_327E159CF35F8F80ACE6997A0DE0BB52" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Numerator: </link:label>
<link:label id="lab_it_NumeratorAbstract_327E159CF35F8F80ACE6997A0DE0BB52_label_en-US" xlink:label="lab_it_NumeratorAbstract_327E159CF35F8F80ACE6997A0DE0BB52" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Numerator: [Abstract] </link:label>
<link:label id="lab_it_NumeratorAbstract_327E159CF35F8F80ACE6997A0DE0BB52_documentation_en-US" xlink:label="lab_it_NumeratorAbstract_327E159CF35F8F80ACE6997A0DE0BB52" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US"> -- None. No documentation exists for this element. -- </link:label>
<link:loc xlink:href="it-20161231.xsd#it_NumeratorAbstract" xlink:label="loc_it_NumeratorAbstract_327E159CF35F8F80ACE6997A0DE0BB52" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_it_NumeratorAbstract_327E159CF35F8F80ACE6997A0DE0BB52" xlink:to="lab_it_NumeratorAbstract_327E159CF35F8F80ACE6997A0DE0BB52" xlink:type="arc"/>
<link:label id="lab_us-gaap_NetIncomeLoss_1E2AD64649FB62122391997A0DE0F321_netLabel_en-US" xlink:label="lab_us-gaap_NetIncomeLoss_1E2AD64649FB62122391997A0DE0F321" xlink:role="http://www.xbrl.org/2009/role/netLabel" xlink:type="resource" xml:lang="en-US"> Net income used for calculating basic and diluted earnings per common share </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_NetIncomeLoss" xlink:label="loc_us-gaap_NetIncomeLoss_1E2AD64649FB62122391997A0DE0F321" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_NetIncomeLoss_1E2AD64649FB62122391997A0DE0F321" xlink:to="lab_us-gaap_NetIncomeLoss_1E2AD64649FB62122391997A0DE0F321" xlink:type="arc"/>
<link:label id="lab_it_Denominator1Abstract_4E4858ECF62383AE3964997A0DE0497C_terseLabel_en-US" xlink:label="lab_it_Denominator1Abstract_4E4858ECF62383AE3964997A0DE0497C" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Denominator: </link:label>
<link:label id="lab_it_Denominator1Abstract_4E4858ECF62383AE3964997A0DE0497C_label_en-US" xlink:label="lab_it_Denominator1Abstract_4E4858ECF62383AE3964997A0DE0497C" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Denominator: (1) [Abstract] </link:label>
<link:label id="lab_it_Denominator1Abstract_4E4858ECF62383AE3964997A0DE0497C_documentation_en-US" xlink:label="lab_it_Denominator1Abstract_4E4858ECF62383AE3964997A0DE0497C" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US"> -- None. No documentation exists for this element. -- </link:label>
<link:loc xlink:href="it-20161231.xsd#it_Denominator1Abstract" xlink:label="loc_it_Denominator1Abstract_4E4858ECF62383AE3964997A0DE0497C" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_it_Denominator1Abstract_4E4858ECF62383AE3964997A0DE0497C" xlink:to="lab_it_Denominator1Abstract_4E4858ECF62383AE3964997A0DE0497C" xlink:type="arc"/>
<link:label id="lab_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_D8C6B8570963CDE036D3997A0DE0FC65_verboseLabel_en-US" xlink:label="lab_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_D8C6B8570963CDE036D3997A0DE0FC65" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:type="resource" xml:lang="en-US"> Weighted average number of common shares used in the calculation of basic earnings per share </link:label>
<link:label id="lab_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_D8C6B8570963CDE036D3997A0DE0FC65_label_en-US" xlink:label="lab_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_D8C6B8570963CDE036D3997A0DE0FC65" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Weighted Average Number of Shares Outstanding, Basic </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_WeightedAverageNumberOfSharesOutstandingBasic" xlink:label="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_D8C6B8570963CDE036D3997A0DE0FC65" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_D8C6B8570963CDE036D3997A0DE0FC65" xlink:to="lab_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_D8C6B8570963CDE036D3997A0DE0FC65" xlink:type="arc"/>
<link:label id="lab_us-gaap_IncrementalCommonSharesAttributableToShareBasedPaymentArrangements_534C25E43E72B66011BB997A0DE0ECEE_terseLabel_en-US" xlink:label="lab_us-gaap_IncrementalCommonSharesAttributableToShareBasedPaymentArrangements_534C25E43E72B66011BB997A0DE0ECEE" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Common share equivalents associated with stock-based compensation plans </link:label>
<link:label id="lab_us-gaap_IncrementalCommonSharesAttributableToShareBasedPaymentArrangements_534C25E43E72B66011BB997A0DE0ECEE_label_en-US" xlink:label="lab_us-gaap_IncrementalCommonSharesAttributableToShareBasedPaymentArrangements_534C25E43E72B66011BB997A0DE0ECEE" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Incremental Common Shares Attributable to Dilutive Effect of Share-based Payment Arrangements </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_IncrementalCommonSharesAttributableToShareBasedPaymentArrangements" xlink:label="loc_us-gaap_IncrementalCommonSharesAttributableToShareBasedPaymentArrangements_534C25E43E72B66011BB997A0DE0ECEE" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_IncrementalCommonSharesAttributableToShareBasedPaymentArrangements_534C25E43E72B66011BB997A0DE0ECEE" xlink:to="lab_us-gaap_IncrementalCommonSharesAttributableToShareBasedPaymentArrangements_534C25E43E72B66011BB997A0DE0ECEE" xlink:type="arc"/>
<link:label id="lab_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_B56D91764DFA38D09F0F997A0DE0C520_totalLabel_en-US" xlink:label="lab_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_B56D91764DFA38D09F0F997A0DE0C520" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:type="resource" xml:lang="en-US"> Shares used in the calculation of diluted earnings per share </link:label>
<link:label id="lab_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_B56D91764DFA38D09F0F997A0DE0C520_label_en-US" xlink:label="lab_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_B56D91764DFA38D09F0F997A0DE0C520" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Weighted Average Number of Shares Outstanding, Diluted </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding" xlink:label="loc_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_B56D91764DFA38D09F0F997A0DE0C520" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_B56D91764DFA38D09F0F997A0DE0C520" xlink:to="lab_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_B56D91764DFA38D09F0F997A0DE0C520" xlink:type="arc"/>
<link:label id="lab_us-gaap_EarningsPerShareBasicAndDilutedAbstract_B282CF6F4757683F6123997A0DE09387_terseLabel_en-US" xlink:label="lab_us-gaap_EarningsPerShareBasicAndDilutedAbstract_B282CF6F4757683F6123997A0DE09387" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Earnings per share: </link:label>
<link:label id="lab_us-gaap_EarningsPerShareBasicAndDilutedAbstract_B282CF6F4757683F6123997A0DE09387_label_en-US" xlink:label="lab_us-gaap_EarningsPerShareBasicAndDilutedAbstract_B282CF6F4757683F6123997A0DE09387" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Earnings Per Share, Basic and Diluted [Abstract] </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_EarningsPerShareBasicAndDilutedAbstract" xlink:label="loc_us-gaap_EarningsPerShareBasicAndDilutedAbstract_B282CF6F4757683F6123997A0DE09387" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_EarningsPerShareBasicAndDilutedAbstract_B282CF6F4757683F6123997A0DE09387" xlink:to="lab_us-gaap_EarningsPerShareBasicAndDilutedAbstract_B282CF6F4757683F6123997A0DE09387" xlink:type="arc"/>
<link:label id="lab_us-gaap_EarningsPerShareBasic_BC7CFBB9553A6D935ED0997A0DE06295_terseLabel_en-US" xlink:label="lab_us-gaap_EarningsPerShareBasic_BC7CFBB9553A6D935ED0997A0DE06295" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Basic (in Dollars per share) </link:label>
<link:label id="lab_us-gaap_EarningsPerShareBasic_BC7CFBB9553A6D935ED0997A0DE06295_label_en-US" xlink:label="lab_us-gaap_EarningsPerShareBasic_BC7CFBB9553A6D935ED0997A0DE06295" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Earnings Per Share, Basic </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_EarningsPerShareBasic" xlink:label="loc_us-gaap_EarningsPerShareBasic_BC7CFBB9553A6D935ED0997A0DE06295" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_EarningsPerShareBasic_BC7CFBB9553A6D935ED0997A0DE06295" xlink:to="lab_us-gaap_EarningsPerShareBasic_BC7CFBB9553A6D935ED0997A0DE06295" xlink:type="arc"/>
<link:label id="lab_us-gaap_EarningsPerShareDiluted_CB4D387D90B1F2A51792997A0DE0848E_terseLabel_en-US" xlink:label="lab_us-gaap_EarningsPerShareDiluted_CB4D387D90B1F2A51792997A0DE0848E" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Diluted (in Dollars per share) </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_EarningsPerShareDiluted" xlink:label="loc_us-gaap_EarningsPerShareDiluted_CB4D387D90B1F2A51792997A0DE0848E" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_EarningsPerShareDiluted_CB4D387D90B1F2A51792997A0DE0848E" xlink:to="lab_us-gaap_EarningsPerShareDiluted_CB4D387D90B1F2A51792997A0DE0848E" xlink:type="arc"/>
<link:label id="lab_us-gaap_DefinedBenefitPlanBenefitObligation_2827EEAF61574CB68EDD3E9435C90CBC_periodStartLabel_en-US" xlink:label="lab_us-gaap_DefinedBenefitPlanBenefitObligation_2827EEAF61574CB68EDD3E9435C90CBC" xlink:role="http://www.xbrl.org/2003/role/periodStartLabel" xlink:type="resource" xml:lang="en-US"> Projected benefit obligation at beginning of year </link:label>
<link:label id="lab_us-gaap_DefinedBenefitPlanBenefitObligation_2827EEAF61574CB68EDD3E9435C90CBC_label_en-US" xlink:label="lab_us-gaap_DefinedBenefitPlanBenefitObligation_2827EEAF61574CB68EDD3E9435C90CBC" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Defined Benefit Plan, Benefit Obligation </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_DefinedBenefitPlanBenefitObligation" xlink:label="loc_us-gaap_DefinedBenefitPlanBenefitObligation_2827EEAF61574CB68EDD3E9435C90CBC" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DefinedBenefitPlanBenefitObligation_2827EEAF61574CB68EDD3E9435C90CBC" xlink:to="lab_us-gaap_DefinedBenefitPlanBenefitObligation_2827EEAF61574CB68EDD3E9435C90CBC" xlink:type="arc"/>
<link:label id="lab_it_DefinedBenefitPlanActuarialGainsLosses_8BDFBA972FEE100C21313E9435C93C23_terseLabel_en-US" xlink:label="lab_it_DefinedBenefitPlanActuarialGainsLosses_8BDFBA972FEE100C21313E9435C93C23" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Actuarial loss (gain) due to assumption changes and plan experience </link:label>
<link:label id="lab_it_DefinedBenefitPlanActuarialGainsLosses_8BDFBA972FEE100C21313E9435C93C23_label_en-US" xlink:label="lab_it_DefinedBenefitPlanActuarialGainsLosses_8BDFBA972FEE100C21313E9435C93C23" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Actuarial loss (gain) due to assumption changes (1) </link:label>
<link:label id="lab_it_DefinedBenefitPlanActuarialGainsLosses_8BDFBA972FEE100C21313E9435C93C23_documentation_en-US" xlink:label="lab_it_DefinedBenefitPlanActuarialGainsLosses_8BDFBA972FEE100C21313E9435C93C23" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US"> The net increase or decrease of changes in the value of the benefit obligation resulting from experience different from that assumed or from a change in an actuarial assumption, or the consequence of a decision to temporarily deviate from the substantive plan. </link:label>
<link:loc xlink:href="it-20161231.xsd#it_DefinedBenefitPlanActuarialGainsLosses" xlink:label="loc_it_DefinedBenefitPlanActuarialGainsLosses_8BDFBA972FEE100C21313E9435C93C23" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_it_DefinedBenefitPlanActuarialGainsLosses_8BDFBA972FEE100C21313E9435C93C23" xlink:to="lab_it_DefinedBenefitPlanActuarialGainsLosses_8BDFBA972FEE100C21313E9435C93C23" xlink:type="arc"/>
<link:label id="lab_us-gaap_DefinedBenefitPlanPlanAmendments_7F6F1009E74334F23D143E9435CA7626_terseLabel_en-US" xlink:label="lab_us-gaap_DefinedBenefitPlanPlanAmendments_7F6F1009E74334F23D143E9435CA7626" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Additions and contractual termination benefits </link:label>
<link:label id="lab_us-gaap_DefinedBenefitPlanPlanAmendments_7F6F1009E74334F23D143E9435CA7626_label_en-US" xlink:label="lab_us-gaap_DefinedBenefitPlanPlanAmendments_7F6F1009E74334F23D143E9435CA7626" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Defined Benefit Plan, Plan Amendments </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_DefinedBenefitPlanPlanAmendments" xlink:label="loc_us-gaap_DefinedBenefitPlanPlanAmendments_7F6F1009E74334F23D143E9435CA7626" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DefinedBenefitPlanPlanAmendments_7F6F1009E74334F23D143E9435CA7626" xlink:to="lab_us-gaap_DefinedBenefitPlanPlanAmendments_7F6F1009E74334F23D143E9435CA7626" xlink:type="arc"/>
<link:label id="lab_us-gaap_DefinedBenefitPlanBenefitsPaid_5EA9859EC16B7E437A493E9435CA60A1_negatedTerseLabel_en-US" xlink:label="lab_us-gaap_DefinedBenefitPlanBenefitsPaid_5EA9859EC16B7E437A493E9435CA60A1" xlink:role="http://www.xbrl.org/2009/role/negatedTerseLabel" xlink:type="resource" xml:lang="en-US"> Benefits paid </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_DefinedBenefitPlanBenefitsPaid" xlink:label="loc_us-gaap_DefinedBenefitPlanBenefitsPaid_5EA9859EC16B7E437A493E9435CA60A1" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DefinedBenefitPlanBenefitsPaid_5EA9859EC16B7E437A493E9435CA60A1" xlink:to="lab_us-gaap_DefinedBenefitPlanBenefitsPaid_5EA9859EC16B7E437A493E9435CA60A1" xlink:type="arc"/>
<link:label id="lab_us-gaap_DefinedBenefitPlanForeignCurrencyExchangeRateChangesBenefitObligation_8727644BACB39A84921F3E9435CA9BA1_terseLabel_en-US" xlink:label="lab_us-gaap_DefinedBenefitPlanForeignCurrencyExchangeRateChangesBenefitObligation_8727644BACB39A84921F3E9435CA9BA1" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Foreign currency impact </link:label>
<link:label id="lab_us-gaap_DefinedBenefitPlanForeignCurrencyExchangeRateChangesBenefitObligation_8727644BACB39A84921F3E9435CA9BA1_label_en-US" xlink:label="lab_us-gaap_DefinedBenefitPlanForeignCurrencyExchangeRateChangesBenefitObligation_8727644BACB39A84921F3E9435CA9BA1" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Defined Benefit Plan, Foreign Currency Exchange Rate Gain (Loss) </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_DefinedBenefitPlanForeignCurrencyExchangeRateChangesBenefitObligation" xlink:label="loc_us-gaap_DefinedBenefitPlanForeignCurrencyExchangeRateChangesBenefitObligation_8727644BACB39A84921F3E9435CA9BA1" xlink:type="locator"/>
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<link:label id="lab_us-gaap_DefinedBenefitPlanBenefitObligation_6F256C0E24266FF976CD3E9435CACD23_periodEndLabel_en-US" xlink:label="lab_us-gaap_DefinedBenefitPlanBenefitObligation_6F256C0E24266FF976CD3E9435CACD23" xlink:role="http://www.xbrl.org/2003/role/periodEndLabel" xlink:type="resource" xml:lang="en-US"> Projected benefit obligation at end of year </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_DefinedBenefitPlanBenefitObligation" xlink:label="loc_us-gaap_DefinedBenefitPlanBenefitObligation_6F256C0E24266FF976CD3E9435CACD23" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DefinedBenefitPlanBenefitObligation_6F256C0E24266FF976CD3E9435CACD23" xlink:to="lab_us-gaap_DefinedBenefitPlanBenefitObligation_6F256C0E24266FF976CD3E9435CACD23" xlink:type="arc"/>
<link:label id="lab_us-gaap_LetterOfCreditMember_F3E5B329129DF101EDE35E3EE746ACE7_terseLabel_en-US" xlink:label="lab_us-gaap_LetterOfCreditMember_F3E5B329129DF101EDE35E3EE746ACE7" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Letter of credit </link:label>
<link:label id="lab_us-gaap_LetterOfCreditMember_F3E5B329129DF101EDE35E3EE746ACE7_label_en-US" xlink:label="lab_us-gaap_LetterOfCreditMember_F3E5B329129DF101EDE35E3EE746ACE7" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Letter of Credit [Member] </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_LetterOfCreditMember" xlink:label="loc_us-gaap_LetterOfCreditMember_F3E5B329129DF101EDE35E3EE746ACE7" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_LetterOfCreditMember_F3E5B329129DF101EDE35E3EE746ACE7" xlink:to="lab_us-gaap_LetterOfCreditMember_F3E5B329129DF101EDE35E3EE746ACE7" xlink:type="arc"/>
<link:label id="lab_us-gaap_VariableRateAxis_21A74CFDCDD0AFDAC3475E3EE748C269_terseLabel_en-US" xlink:label="lab_us-gaap_VariableRateAxis_21A74CFDCDD0AFDAC3475E3EE748C269" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Variable Rate [Axis] </link:label>
<link:label id="lab_us-gaap_VariableRateAxis_21A74CFDCDD0AFDAC3475E3EE748C269_label_en-US" xlink:label="lab_us-gaap_VariableRateAxis_21A74CFDCDD0AFDAC3475E3EE748C269" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Variable Rate [Axis] </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_VariableRateAxis" xlink:label="loc_us-gaap_VariableRateAxis_21A74CFDCDD0AFDAC3475E3EE748C269" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_VariableRateAxis_21A74CFDCDD0AFDAC3475E3EE748C269" xlink:to="lab_us-gaap_VariableRateAxis_21A74CFDCDD0AFDAC3475E3EE748C269" xlink:type="arc"/>
<link:label id="lab_us-gaap_VariableRateDomain_5C416757B658469BD2275E3EE748A435_terseLabel_en-US" xlink:label="lab_us-gaap_VariableRateDomain_5C416757B658469BD2275E3EE748A435" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Variable Rate [Domain] </link:label>
<link:label id="lab_us-gaap_VariableRateDomain_5C416757B658469BD2275E3EE748A435_label_en-US" xlink:label="lab_us-gaap_VariableRateDomain_5C416757B658469BD2275E3EE748A435" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Variable Rate [Domain] </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_VariableRateDomain" xlink:label="loc_us-gaap_VariableRateDomain_5C416757B658469BD2275E3EE748A435" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_VariableRateDomain_5C416757B658469BD2275E3EE748A435" xlink:to="lab_us-gaap_VariableRateDomain_5C416757B658469BD2275E3EE748A435" xlink:type="arc"/>
<link:label id="lab_it_EuroDollarRateMember_4F3DCE8854204AE880D35E3EE74876C6_terseLabel_en-US" xlink:label="lab_it_EuroDollarRateMember_4F3DCE8854204AE880D35E3EE74876C6" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Euro Dollar rate </link:label>
<link:label id="lab_it_EuroDollarRateMember_4F3DCE8854204AE880D35E3EE74876C6_label_en-US" xlink:label="lab_it_EuroDollarRateMember_4F3DCE8854204AE880D35E3EE74876C6" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Euro Dollar Rate [Member] </link:label>
<link:label id="lab_it_EuroDollarRateMember_4F3DCE8854204AE880D35E3EE74876C6_documentation_en-US" xlink:label="lab_it_EuroDollarRateMember_4F3DCE8854204AE880D35E3EE74876C6" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US"> -- None. No documentation exists for this element. -- </link:label>
<link:loc xlink:href="it-20161231.xsd#it_EuroDollarRateMember" xlink:label="loc_it_EuroDollarRateMember_4F3DCE8854204AE880D35E3EE74876C6" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_it_EuroDollarRateMember_4F3DCE8854204AE880D35E3EE74876C6" xlink:to="lab_it_EuroDollarRateMember_4F3DCE8854204AE880D35E3EE74876C6" xlink:type="arc"/>
<link:label id="lab_us-gaap_InterestRateContractMember_ADC6CF9F50A818E37ABE5E3EE74885D1_terseLabel_en-US" xlink:label="lab_us-gaap_InterestRateContractMember_ADC6CF9F50A818E37ABE5E3EE74885D1" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Interest Rate Contract </link:label>
<link:label id="lab_us-gaap_InterestRateContractMember_ADC6CF9F50A818E37ABE5E3EE74885D1_label_en-US" xlink:label="lab_us-gaap_InterestRateContractMember_ADC6CF9F50A818E37ABE5E3EE74885D1" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Interest Rate Contract [Member] </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_InterestRateContractMember" xlink:label="loc_us-gaap_InterestRateContractMember_ADC6CF9F50A818E37ABE5E3EE74885D1" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_InterestRateContractMember_ADC6CF9F50A818E37ABE5E3EE74885D1" xlink:to="lab_us-gaap_InterestRateContractMember_ADC6CF9F50A818E37ABE5E3EE74885D1" xlink:type="arc"/>
<link:label id="lab_us-gaap_InterestRateSwapMember_C8837DDB5BE4FF4A05055E3EE748F0EF_terseLabel_en-US" xlink:label="lab_us-gaap_InterestRateSwapMember_C8837DDB5BE4FF4A05055E3EE748F0EF" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Interest rate swap </link:label>
<link:label id="lab_us-gaap_InterestRateSwapMember_C8837DDB5BE4FF4A05055E3EE748F0EF_label_en-US" xlink:label="lab_us-gaap_InterestRateSwapMember_C8837DDB5BE4FF4A05055E3EE748F0EF" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Interest Rate Swap [Member] </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_InterestRateSwapMember" xlink:label="loc_us-gaap_InterestRateSwapMember_C8837DDB5BE4FF4A05055E3EE748F0EF" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_InterestRateSwapMember_C8837DDB5BE4FF4A05055E3EE748F0EF" xlink:to="lab_us-gaap_InterestRateSwapMember_C8837DDB5BE4FF4A05055E3EE748F0EF" xlink:type="arc"/>
<link:label id="lab_us-gaap_InvestmentTypeAxis_5FF2ECF35E1E6DFEB4715E3EE748B617_terseLabel_en-US" xlink:label="lab_us-gaap_InvestmentTypeAxis_5FF2ECF35E1E6DFEB4715E3EE748B617" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Investment Type [Axis] </link:label>
<link:label id="lab_us-gaap_InvestmentTypeAxis_5FF2ECF35E1E6DFEB4715E3EE748B617_label_en-US" xlink:label="lab_us-gaap_InvestmentTypeAxis_5FF2ECF35E1E6DFEB4715E3EE748B617" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Investment Type [Axis] </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_InvestmentTypeAxis" xlink:label="loc_us-gaap_InvestmentTypeAxis_5FF2ECF35E1E6DFEB4715E3EE748B617" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_InvestmentTypeAxis_5FF2ECF35E1E6DFEB4715E3EE748B617" xlink:to="lab_us-gaap_InvestmentTypeAxis_5FF2ECF35E1E6DFEB4715E3EE748B617" xlink:type="arc"/>
<link:label id="lab_us-gaap_InvestmentTypeCategorizationMember_D56C8796BC30E0F9EB595E3EE74844E6_terseLabel_en-US" xlink:label="lab_us-gaap_InvestmentTypeCategorizationMember_D56C8796BC30E0F9EB595E3EE74844E6" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Investments [Domain] </link:label>
<link:label id="lab_us-gaap_InvestmentTypeCategorizationMember_D56C8796BC30E0F9EB595E3EE74844E6_label_en-US" xlink:label="lab_us-gaap_InvestmentTypeCategorizationMember_D56C8796BC30E0F9EB595E3EE74844E6" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Investments [Domain] </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_InvestmentTypeCategorizationMember" xlink:label="loc_us-gaap_InvestmentTypeCategorizationMember_D56C8796BC30E0F9EB595E3EE74844E6" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_InvestmentTypeCategorizationMember_D56C8796BC30E0F9EB595E3EE74844E6" xlink:to="lab_us-gaap_InvestmentTypeCategorizationMember_D56C8796BC30E0F9EB595E3EE74844E6" xlink:type="arc"/>
<link:label id="lab_us-gaap_DebtInstrumentAxis_541D442BBA4B39564F6D5E3EE7494C12_terseLabel_en-US" xlink:label="lab_us-gaap_DebtInstrumentAxis_541D442BBA4B39564F6D5E3EE7494C12" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Debt Instrument [Axis] </link:label>
<link:label id="lab_us-gaap_DebtInstrumentAxis_541D442BBA4B39564F6D5E3EE7494C12_label_en-US" xlink:label="lab_us-gaap_DebtInstrumentAxis_541D442BBA4B39564F6D5E3EE7494C12" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Debt Instrument [Axis] </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_DebtInstrumentAxis" xlink:label="loc_us-gaap_DebtInstrumentAxis_541D442BBA4B39564F6D5E3EE7494C12" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DebtInstrumentAxis_541D442BBA4B39564F6D5E3EE7494C12" xlink:to="lab_us-gaap_DebtInstrumentAxis_541D442BBA4B39564F6D5E3EE7494C12" xlink:type="arc"/>
<link:label id="lab_us-gaap_DebtInstrumentNameDomain_F8D194D967C8E8C390FF5E3EE749EB02_terseLabel_en-US" xlink:label="lab_us-gaap_DebtInstrumentNameDomain_F8D194D967C8E8C390FF5E3EE749EB02" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Debt Instrument, Name [Domain] </link:label>
<link:label id="lab_us-gaap_DebtInstrumentNameDomain_F8D194D967C8E8C390FF5E3EE749EB02_label_en-US" xlink:label="lab_us-gaap_DebtInstrumentNameDomain_F8D194D967C8E8C390FF5E3EE749EB02" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Debt Instrument, Name [Domain] </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_DebtInstrumentNameDomain" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_F8D194D967C8E8C390FF5E3EE749EB02" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_F8D194D967C8E8C390FF5E3EE749EB02" xlink:to="lab_us-gaap_DebtInstrumentNameDomain_F8D194D967C8E8C390FF5E3EE749EB02" xlink:type="arc"/>
<link:label id="lab_it_FederalFundsRateMember_28A9A2E4BAF58FB5247D5E3EE749C79A_terseLabel_en-US" xlink:label="lab_it_FederalFundsRateMember_28A9A2E4BAF58FB5247D5E3EE749C79A" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Federal Funds rate </link:label>
<link:label id="lab_it_FederalFundsRateMember_28A9A2E4BAF58FB5247D5E3EE749C79A_label_en-US" xlink:label="lab_it_FederalFundsRateMember_28A9A2E4BAF58FB5247D5E3EE749C79A" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Federal Funds Rate [Member] </link:label>
<link:label id="lab_it_FederalFundsRateMember_28A9A2E4BAF58FB5247D5E3EE749C79A_documentation_en-US" xlink:label="lab_it_FederalFundsRateMember_28A9A2E4BAF58FB5247D5E3EE749C79A" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US"> -- None. No documentation exists for this element. -- </link:label>
<link:loc xlink:href="it-20161231.xsd#it_FederalFundsRateMember" xlink:label="loc_it_FederalFundsRateMember_28A9A2E4BAF58FB5247D5E3EE749C79A" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_it_FederalFundsRateMember_28A9A2E4BAF58FB5247D5E3EE749C79A" xlink:to="lab_it_FederalFundsRateMember_28A9A2E4BAF58FB5247D5E3EE749C79A" xlink:type="arc"/>
<link:label id="lab_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_16A48CF4CF2AEE60C3D65E3EE749A2C2_terseLabel_en-US" xlink:label="lab_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_16A48CF4CF2AEE60C3D65E3EE749A2C2" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Line of credit facility, maximum borrowing capacity </link:label>
<link:label id="lab_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_16A48CF4CF2AEE60C3D65E3EE749A2C2_label_en-US" xlink:label="lab_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_16A48CF4CF2AEE60C3D65E3EE749A2C2" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Line of Credit Facility, Maximum Borrowing Capacity </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity" xlink:label="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_16A48CF4CF2AEE60C3D65E3EE749A2C2" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_16A48CF4CF2AEE60C3D65E3EE749A2C2" xlink:to="lab_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_16A48CF4CF2AEE60C3D65E3EE749A2C2" xlink:type="arc"/>
<link:label id="lab_us-gaap_LineOfCreditFacilityCurrentBorrowingCapacity_2D42CC9490504F2E82425E3EE74962D7_terseLabel_en-US" xlink:label="lab_us-gaap_LineOfCreditFacilityCurrentBorrowingCapacity_2D42CC9490504F2E82425E3EE74962D7" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Line of credit facility, current borrowing capacity </link:label>
<link:label id="lab_us-gaap_LineOfCreditFacilityCurrentBorrowingCapacity_2D42CC9490504F2E82425E3EE74962D7_label_en-US" xlink:label="lab_us-gaap_LineOfCreditFacilityCurrentBorrowingCapacity_2D42CC9490504F2E82425E3EE74962D7" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Line of Credit Facility, Current Borrowing Capacity </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_LineOfCreditFacilityCurrentBorrowingCapacity" xlink:label="loc_us-gaap_LineOfCreditFacilityCurrentBorrowingCapacity_2D42CC9490504F2E82425E3EE74962D7" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_LineOfCreditFacilityCurrentBorrowingCapacity_2D42CC9490504F2E82425E3EE74962D7" xlink:to="lab_us-gaap_LineOfCreditFacilityCurrentBorrowingCapacity_2D42CC9490504F2E82425E3EE74962D7" xlink:type="arc"/>
<link:label id="lab_it_LineofCreditFacilityFrequencyofPaymentsNumberofQuarterlyInstallments_0EF5F6687544C7BDF12D5E3EE749028A_terseLabel_en-US" xlink:label="lab_it_LineofCreditFacilityFrequencyofPaymentsNumberofQuarterlyInstallments_0EF5F6687544C7BDF12D5E3EE749028A" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Line of credit facility, frequency of payments in quarterly installments </link:label>
<link:label id="lab_it_LineofCreditFacilityFrequencyofPaymentsNumberofQuarterlyInstallments_0EF5F6687544C7BDF12D5E3EE749028A_label_en-US" xlink:label="lab_it_LineofCreditFacilityFrequencyofPaymentsNumberofQuarterlyInstallments_0EF5F6687544C7BDF12D5E3EE749028A" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Line of Credit Facility, Frequency of Payments, Number of Quarterly Installments </link:label>
<link:label id="lab_it_LineofCreditFacilityFrequencyofPaymentsNumberofQuarterlyInstallments_0EF5F6687544C7BDF12D5E3EE749028A_documentation_en-US" xlink:label="lab_it_LineofCreditFacilityFrequencyofPaymentsNumberofQuarterlyInstallments_0EF5F6687544C7BDF12D5E3EE749028A" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US"> Line of Credit Facility, Frequency of Payments, Number of Quarterly Installments </link:label>
<link:loc xlink:href="it-20161231.xsd#it_LineofCreditFacilityFrequencyofPaymentsNumberofQuarterlyInstallments" xlink:label="loc_it_LineofCreditFacilityFrequencyofPaymentsNumberofQuarterlyInstallments_0EF5F6687544C7BDF12D5E3EE749028A" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_it_LineofCreditFacilityFrequencyofPaymentsNumberofQuarterlyInstallments_0EF5F6687544C7BDF12D5E3EE749028A" xlink:to="lab_it_LineofCreditFacilityFrequencyofPaymentsNumberofQuarterlyInstallments_0EF5F6687544C7BDF12D5E3EE749028A" xlink:type="arc"/>
<link:label id="lab_it_DebtInstrumentInterestAdditionalInterestAboveFederalFundRate_D5A6CAA12D292D0746015E3EE7495258_terseLabel_en-US" xlink:label="lab_it_DebtInstrumentInterestAdditionalInterestAboveFederalFundRate_D5A6CAA12D292D0746015E3EE7495258" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Debt instrument, interest, additional interest above federal fund rate </link:label>
<link:label id="lab_it_DebtInstrumentInterestAdditionalInterestAboveFederalFundRate_D5A6CAA12D292D0746015E3EE7495258_label_en-US" xlink:label="lab_it_DebtInstrumentInterestAdditionalInterestAboveFederalFundRate_D5A6CAA12D292D0746015E3EE7495258" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Debt Instrument Interest Additional Interest Above Federal Fund Rate </link:label>
<link:label id="lab_it_DebtInstrumentInterestAdditionalInterestAboveFederalFundRate_D5A6CAA12D292D0746015E3EE7495258_documentation_en-US" xlink:label="lab_it_DebtInstrumentInterestAdditionalInterestAboveFederalFundRate_D5A6CAA12D292D0746015E3EE7495258" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US"> Debt instrument interest additional interest above federal fund rate. </link:label>
<link:loc xlink:href="it-20161231.xsd#it_DebtInstrumentInterestAdditionalInterestAboveFederalFundRate" xlink:label="loc_it_DebtInstrumentInterestAdditionalInterestAboveFederalFundRate_D5A6CAA12D292D0746015E3EE7495258" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_it_DebtInstrumentInterestAdditionalInterestAboveFederalFundRate_D5A6CAA12D292D0746015E3EE7495258" xlink:to="lab_it_DebtInstrumentInterestAdditionalInterestAboveFederalFundRate_D5A6CAA12D292D0746015E3EE7495258" xlink:type="arc"/>
<link:label id="lab_it_DebtInstrumentInterestAdditionalInterestAboveEurodollarRate_9D39C44575D71F1F80DB5E3EE74A67D3_terseLabel_en-US" xlink:label="lab_it_DebtInstrumentInterestAdditionalInterestAboveEurodollarRate_9D39C44575D71F1F80DB5E3EE74A67D3" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Debt instrument, interest, additional interest above eurodollar rate </link:label>
<link:label id="lab_it_DebtInstrumentInterestAdditionalInterestAboveEurodollarRate_9D39C44575D71F1F80DB5E3EE74A67D3_label_en-US" xlink:label="lab_it_DebtInstrumentInterestAdditionalInterestAboveEurodollarRate_9D39C44575D71F1F80DB5E3EE74A67D3" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Debt Instrument Interest Additional Interest Above Euro dollar Rate </link:label>
<link:label id="lab_it_DebtInstrumentInterestAdditionalInterestAboveEurodollarRate_9D39C44575D71F1F80DB5E3EE74A67D3_documentation_en-US" xlink:label="lab_it_DebtInstrumentInterestAdditionalInterestAboveEurodollarRate_9D39C44575D71F1F80DB5E3EE74A67D3" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US"> Debt instrument interest additional interest above eurodollar rate. </link:label>
<link:loc xlink:href="it-20161231.xsd#it_DebtInstrumentInterestAdditionalInterestAboveEurodollarRate" xlink:label="loc_it_DebtInstrumentInterestAdditionalInterestAboveEurodollarRate_9D39C44575D71F1F80DB5E3EE74A67D3" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_it_DebtInstrumentInterestAdditionalInterestAboveEurodollarRate_9D39C44575D71F1F80DB5E3EE74A67D3" xlink:to="lab_it_DebtInstrumentInterestAdditionalInterestAboveEurodollarRate_9D39C44575D71F1F80DB5E3EE74A67D3" xlink:type="arc"/>
<link:label id="lab_it_MinimumApplicableMarginRate_49A48EF0711BED4FCE3A5E3EE74A1A8D_terseLabel_en-US" xlink:label="lab_it_MinimumApplicableMarginRate_49A48EF0711BED4FCE3A5E3EE74A1A8D" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Minimum applicable margin rate </link:label>
<link:label id="lab_it_MinimumApplicableMarginRate_49A48EF0711BED4FCE3A5E3EE74A1A8D_label_en-US" xlink:label="lab_it_MinimumApplicableMarginRate_49A48EF0711BED4FCE3A5E3EE74A1A8D" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Minimum Applicable Margin Rate </link:label>
<link:label id="lab_it_MinimumApplicableMarginRate_49A48EF0711BED4FCE3A5E3EE74A1A8D_documentation_en-US" xlink:label="lab_it_MinimumApplicableMarginRate_49A48EF0711BED4FCE3A5E3EE74A1A8D" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US"> Minimum applicable margin rate. </link:label>
<link:loc xlink:href="it-20161231.xsd#it_MinimumApplicableMarginRate" xlink:label="loc_it_MinimumApplicableMarginRate_49A48EF0711BED4FCE3A5E3EE74A1A8D" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_it_MinimumApplicableMarginRate_49A48EF0711BED4FCE3A5E3EE74A1A8D" xlink:to="lab_it_MinimumApplicableMarginRate_49A48EF0711BED4FCE3A5E3EE74A1A8D" xlink:type="arc"/>
<link:label id="lab_it_MaximumApplicableMarginRate_8E5A878222CD7C5A75FB5E3EE74A17A4_terseLabel_en-US" xlink:label="lab_it_MaximumApplicableMarginRate_8E5A878222CD7C5A75FB5E3EE74A17A4" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Maximum applicable margin rate </link:label>
<link:label id="lab_it_MaximumApplicableMarginRate_8E5A878222CD7C5A75FB5E3EE74A17A4_label_en-US" xlink:label="lab_it_MaximumApplicableMarginRate_8E5A878222CD7C5A75FB5E3EE74A17A4" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Maximum Applicable Margin Rate </link:label>
<link:label id="lab_it_MaximumApplicableMarginRate_8E5A878222CD7C5A75FB5E3EE74A17A4_documentation_en-US" xlink:label="lab_it_MaximumApplicableMarginRate_8E5A878222CD7C5A75FB5E3EE74A17A4" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US"> Maximum applicable margin rate. </link:label>
<link:loc xlink:href="it-20161231.xsd#it_MaximumApplicableMarginRate" xlink:label="loc_it_MaximumApplicableMarginRate_8E5A878222CD7C5A75FB5E3EE74A17A4" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_it_MaximumApplicableMarginRate_8E5A878222CD7C5A75FB5E3EE74A17A4" xlink:to="lab_it_MaximumApplicableMarginRate_8E5A878222CD7C5A75FB5E3EE74A17A4" xlink:type="arc"/>
<link:label id="lab_us-gaap_LineOfCreditFacilityInterestRateAtPeriodEnd_CE2C980FC74C4673967D5E3EE74AFCD7_terseLabel_en-US" xlink:label="lab_us-gaap_LineOfCreditFacilityInterestRateAtPeriodEnd_CE2C980FC74C4673967D5E3EE74AFCD7" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Interest rate at period end </link:label>
<link:label id="lab_us-gaap_LineOfCreditFacilityInterestRateAtPeriodEnd_CE2C980FC74C4673967D5E3EE74AFCD7_label_en-US" xlink:label="lab_us-gaap_LineOfCreditFacilityInterestRateAtPeriodEnd_CE2C980FC74C4673967D5E3EE74AFCD7" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Line of Credit Facility, Interest Rate at Period End </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_LineOfCreditFacilityInterestRateAtPeriodEnd" xlink:label="loc_us-gaap_LineOfCreditFacilityInterestRateAtPeriodEnd_CE2C980FC74C4673967D5E3EE74AFCD7" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_LineOfCreditFacilityInterestRateAtPeriodEnd_CE2C980FC74C4673967D5E3EE74AFCD7" xlink:to="lab_us-gaap_LineOfCreditFacilityInterestRateAtPeriodEnd_CE2C980FC74C4673967D5E3EE74AFCD7" xlink:type="arc"/>
<link:label id="lab_it_DebtInstrumentInterestBaseRate_32154BD38DBBF93EE58B5E3EE74A8759_terseLabel_en-US" xlink:label="lab_it_DebtInstrumentInterestBaseRate_32154BD38DBBF93EE58B5E3EE74A8759" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Debt instrument, interest base rate </link:label>
<link:label id="lab_it_DebtInstrumentInterestBaseRate_32154BD38DBBF93EE58B5E3EE74A8759_label_en-US" xlink:label="lab_it_DebtInstrumentInterestBaseRate_32154BD38DBBF93EE58B5E3EE74A8759" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Debt Instrument Interest Base Rate </link:label>
<link:label id="lab_it_DebtInstrumentInterestBaseRate_32154BD38DBBF93EE58B5E3EE74A8759_documentation_en-US" xlink:label="lab_it_DebtInstrumentInterestBaseRate_32154BD38DBBF93EE58B5E3EE74A8759" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US"> Debt instrument interest base rate. </link:label>
<link:loc xlink:href="it-20161231.xsd#it_DebtInstrumentInterestBaseRate" xlink:label="loc_it_DebtInstrumentInterestBaseRate_32154BD38DBBF93EE58B5E3EE74A8759" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_it_DebtInstrumentInterestBaseRate_32154BD38DBBF93EE58B5E3EE74A8759" xlink:to="lab_it_DebtInstrumentInterestBaseRate_32154BD38DBBF93EE58B5E3EE74A8759" xlink:type="arc"/>
<link:label id="lab_it_DebtInstrumentInterestAdditionalInterestaboveBaseRate_21A056CA54C2979AFE1A5E3EE74A7913_terseLabel_en-US" xlink:label="lab_it_DebtInstrumentInterestAdditionalInterestaboveBaseRate_21A056CA54C2979AFE1A5E3EE74A7913" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Debt instrument, interest, additional interest above base rate </link:label>
<link:label id="lab_it_DebtInstrumentInterestAdditionalInterestaboveBaseRate_21A056CA54C2979AFE1A5E3EE74A7913_label_en-US" xlink:label="lab_it_DebtInstrumentInterestAdditionalInterestaboveBaseRate_21A056CA54C2979AFE1A5E3EE74A7913" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Debt Instrument Interest Additional Interest above Base Rate </link:label>
<link:label id="lab_it_DebtInstrumentInterestAdditionalInterestaboveBaseRate_21A056CA54C2979AFE1A5E3EE74A7913_documentation_en-US" xlink:label="lab_it_DebtInstrumentInterestAdditionalInterestaboveBaseRate_21A056CA54C2979AFE1A5E3EE74A7913" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US"> Debt instrument interest additional interest above base rate. </link:label>
<link:loc xlink:href="it-20161231.xsd#it_DebtInstrumentInterestAdditionalInterestaboveBaseRate" xlink:label="loc_it_DebtInstrumentInterestAdditionalInterestaboveBaseRate_21A056CA54C2979AFE1A5E3EE74A7913" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_it_DebtInstrumentInterestAdditionalInterestaboveBaseRate_21A056CA54C2979AFE1A5E3EE74A7913" xlink:to="lab_it_DebtInstrumentInterestAdditionalInterestaboveBaseRate_21A056CA54C2979AFE1A5E3EE74A7913" xlink:type="arc"/>
<link:label id="lab_invest_DerivativeNotionalAmount_3300646D72802964AA065E3EE74AE61B_verboseLabel_en-US" xlink:label="lab_invest_DerivativeNotionalAmount_3300646D72802964AA065E3EE74AE61B" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:type="resource" xml:lang="en-US"> Contract notional amount </link:label>
<link:label id="lab_invest_DerivativeNotionalAmount_3300646D72802964AA065E3EE74AE61B_label_en-US" xlink:label="lab_invest_DerivativeNotionalAmount_3300646D72802964AA065E3EE74AE61B" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Derivative, Notional Amount </link:label>
<link:loc xlink:href="http://xbrl.sec.gov/invest/2013/invest-2013-01-31.xsd#invest_DerivativeNotionalAmount" xlink:label="loc_invest_DerivativeNotionalAmount_3300646D72802964AA065E3EE74AE61B" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_invest_DerivativeNotionalAmount_3300646D72802964AA065E3EE74AE61B" xlink:to="lab_invest_DerivativeNotionalAmount_3300646D72802964AA065E3EE74AE61B" xlink:type="arc"/>
<link:label id="lab_us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity_8CA32942C3FE62D321A85E3EE74AC0B0_terseLabel_en-US" xlink:label="lab_us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity_8CA32942C3FE62D321A85E3EE74AC0B0" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Line of credit facility, remaining borrowing capacity </link:label>
<link:label id="lab_us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity_8CA32942C3FE62D321A85E3EE74AC0B0_label_en-US" xlink:label="lab_us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity_8CA32942C3FE62D321A85E3EE74AC0B0" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Line of Credit Facility, Remaining Borrowing Capacity </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity" xlink:label="loc_us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity_8CA32942C3FE62D321A85E3EE74AC0B0" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity_8CA32942C3FE62D321A85E3EE74AC0B0" xlink:to="lab_us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity_8CA32942C3FE62D321A85E3EE74AC0B0" xlink:type="arc"/>
<link:label id="lab_us-gaap_DebtInstrumentInterestRateStatedPercentage_99519A0DF28F0B0BF1575E3EE74A317D_terseLabel_en-US" xlink:label="lab_us-gaap_DebtInstrumentInterestRateStatedPercentage_99519A0DF28F0B0BF1575E3EE74A317D" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Debt instrument, fixed interest rate </link:label>
<link:label id="lab_us-gaap_DebtInstrumentInterestRateStatedPercentage_99519A0DF28F0B0BF1575E3EE74A317D_label_en-US" xlink:label="lab_us-gaap_DebtInstrumentInterestRateStatedPercentage_99519A0DF28F0B0BF1575E3EE74A317D" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Debt Instrument, Interest Rate, Stated Percentage </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_DebtInstrumentInterestRateStatedPercentage" xlink:label="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_99519A0DF28F0B0BF1575E3EE74A317D" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_99519A0DF28F0B0BF1575E3EE74A317D" xlink:to="lab_us-gaap_DebtInstrumentInterestRateStatedPercentage_99519A0DF28F0B0BF1575E3EE74A317D" xlink:type="arc"/>
<link:label id="lab_it_DebtInstrumentPrincipalForgivenessProvision_1DB2BCA66CB1F280705D5E3EE74A9404_terseLabel_en-US" xlink:label="lab_it_DebtInstrumentPrincipalForgivenessProvision_1DB2BCA66CB1F280705D5E3EE74A9404" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Line of credit facility, decrease, forgiveness </link:label>
<link:label id="lab_it_DebtInstrumentPrincipalForgivenessProvision_1DB2BCA66CB1F280705D5E3EE74A9404_label_en-US" xlink:label="lab_it_DebtInstrumentPrincipalForgivenessProvision_1DB2BCA66CB1F280705D5E3EE74A9404" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Debt Instrument, Principal Forgiveness Provision </link:label>
<link:label id="lab_it_DebtInstrumentPrincipalForgivenessProvision_1DB2BCA66CB1F280705D5E3EE74A9404_documentation_en-US" xlink:label="lab_it_DebtInstrumentPrincipalForgivenessProvision_1DB2BCA66CB1F280705D5E3EE74A9404" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US"> Debt Instrument, Principal Forgiveness Provision </link:label>
<link:loc xlink:href="it-20161231.xsd#it_DebtInstrumentPrincipalForgivenessProvision" xlink:label="loc_it_DebtInstrumentPrincipalForgivenessProvision_1DB2BCA66CB1F280705D5E3EE74A9404" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_it_DebtInstrumentPrincipalForgivenessProvision_1DB2BCA66CB1F280705D5E3EE74A9404" xlink:to="lab_it_DebtInstrumentPrincipalForgivenessProvision_1DB2BCA66CB1F280705D5E3EE74A9404" xlink:type="arc"/>
<link:label id="lab_us-gaap_DebtInstrumentDecreaseForgiveness_F03526738A067D7D358F5E3EE74A69E9_terseLabel_en-US" xlink:label="lab_us-gaap_DebtInstrumentDecreaseForgiveness_F03526738A067D7D358F5E3EE74A69E9" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Debt instrument, debt forgiveness </link:label>
<link:label id="lab_us-gaap_DebtInstrumentDecreaseForgiveness_F03526738A067D7D358F5E3EE74A69E9_label_en-US" xlink:label="lab_us-gaap_DebtInstrumentDecreaseForgiveness_F03526738A067D7D358F5E3EE74A69E9" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Debt Instrument, Decrease, Forgiveness </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_DebtInstrumentDecreaseForgiveness" xlink:label="loc_us-gaap_DebtInstrumentDecreaseForgiveness_F03526738A067D7D358F5E3EE74A69E9" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DebtInstrumentDecreaseForgiveness_F03526738A067D7D358F5E3EE74A69E9" xlink:to="lab_us-gaap_DebtInstrumentDecreaseForgiveness_F03526738A067D7D358F5E3EE74A69E9" xlink:type="arc"/>
<link:label id="lab_it_LongtermDebtGrossExcludingCurrentMaturities_FA5F381C15C8A81A677B5E3EE74A4D4D_terseLabel_en-US" xlink:label="lab_it_LongtermDebtGrossExcludingCurrentMaturities_FA5F381C15C8A81A677B5E3EE74A4D4D" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Long-term debt, net of deferred financing fees </link:label>
<link:label id="lab_it_LongtermDebtGrossExcludingCurrentMaturities_FA5F381C15C8A81A677B5E3EE74A4D4D_label_en-US" xlink:label="lab_it_LongtermDebtGrossExcludingCurrentMaturities_FA5F381C15C8A81A677B5E3EE74A4D4D" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Long-term Debt, Gross, Excluding Current Maturities </link:label>
<link:label id="lab_it_LongtermDebtGrossExcludingCurrentMaturities_FA5F381C15C8A81A677B5E3EE74A4D4D_documentation_en-US" xlink:label="lab_it_LongtermDebtGrossExcludingCurrentMaturities_FA5F381C15C8A81A677B5E3EE74A4D4D" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US"> Long-term Debt, Gross, Excluding Current Maturities </link:label>
<link:loc xlink:href="it-20161231.xsd#it_LongtermDebtGrossExcludingCurrentMaturities" xlink:label="loc_it_LongtermDebtGrossExcludingCurrentMaturities_FA5F381C15C8A81A677B5E3EE74A4D4D" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_it_LongtermDebtGrossExcludingCurrentMaturities_FA5F381C15C8A81A677B5E3EE74A4D4D" xlink:to="lab_it_LongtermDebtGrossExcludingCurrentMaturities_FA5F381C15C8A81A677B5E3EE74A4D4D" xlink:type="arc"/>
<link:label id="lab_us-gaap_DebtInstrumentInterestRateEffectivePercentage_5540DE40E1DC7834A5ED5E3EE74A9223_terseLabel_en-US" xlink:label="lab_us-gaap_DebtInstrumentInterestRateEffectivePercentage_5540DE40E1DC7834A5ED5E3EE74A9223" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Debt instrument, interest rate at period end </link:label>
<link:label id="lab_us-gaap_DebtInstrumentInterestRateEffectivePercentage_5540DE40E1DC7834A5ED5E3EE74A9223_label_en-US" xlink:label="lab_us-gaap_DebtInstrumentInterestRateEffectivePercentage_5540DE40E1DC7834A5ED5E3EE74A9223" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Debt Instrument, Interest Rate, Effective Percentage </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_DebtInstrumentInterestRateEffectivePercentage" xlink:label="loc_us-gaap_DebtInstrumentInterestRateEffectivePercentage_5540DE40E1DC7834A5ED5E3EE74A9223" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DebtInstrumentInterestRateEffectivePercentage_5540DE40E1DC7834A5ED5E3EE74A9223" xlink:to="lab_us-gaap_DebtInstrumentInterestRateEffectivePercentage_5540DE40E1DC7834A5ED5E3EE74A9223" xlink:type="arc"/>
<link:label id="lab_us-gaap_DerivativeNumberOfInstrumentsHeld_B0510738D9B321D633495E3EE74AFEB8_terseLabel_en-US" xlink:label="lab_us-gaap_DerivativeNumberOfInstrumentsHeld_B0510738D9B321D633495E3EE74AFEB8" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Number of Outstanding Contracts </link:label>
<link:label id="lab_us-gaap_DerivativeNumberOfInstrumentsHeld_B0510738D9B321D633495E3EE74AFEB8_label_en-US" xlink:label="lab_us-gaap_DerivativeNumberOfInstrumentsHeld_B0510738D9B321D633495E3EE74AFEB8" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Derivative, Number of Instruments Held </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_DerivativeNumberOfInstrumentsHeld" xlink:label="loc_us-gaap_DerivativeNumberOfInstrumentsHeld_B0510738D9B321D633495E3EE74AFEB8" xlink:type="locator"/>
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<link:label id="lab_us-gaap_DerivativeFixedInterestRate_ED518924FAF470ED091C5E3EE74A5615_terseLabel_en-US" xlink:label="lab_us-gaap_DerivativeFixedInterestRate_ED518924FAF470ED091C5E3EE74A5615" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Derivative, fixed interest rate </link:label>
<link:label id="lab_us-gaap_DerivativeFixedInterestRate_ED518924FAF470ED091C5E3EE74A5615_label_en-US" xlink:label="lab_us-gaap_DerivativeFixedInterestRate_ED518924FAF470ED091C5E3EE74A5615" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Derivative, Fixed Interest Rate </link:label>
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<link:label id="lab_us-gaap_DerivativeTermOfContract_4BD753BFA9A300365F405E3EE74B2E2B_terseLabel_en-US" xlink:label="lab_us-gaap_DerivativeTermOfContract_4BD753BFA9A300365F405E3EE74B2E2B" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Derivative, term of contract </link:label>
<link:label id="lab_us-gaap_DerivativeTermOfContract_4BD753BFA9A300365F405E3EE74B2E2B_label_en-US" xlink:label="lab_us-gaap_DerivativeTermOfContract_4BD753BFA9A300365F405E3EE74B2E2B" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Derivative, Term of Contract </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_DerivativeTermOfContract" xlink:label="loc_us-gaap_DerivativeTermOfContract_4BD753BFA9A300365F405E3EE74B2E2B" xlink:type="locator"/>
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<link:label id="lab_us-gaap_InterestRateFairValueHedgeDerivativeAtFairValueNet_2951E193C448F6C63DF55E3EE74BF8F5_negatedTerseLabel_en-US" xlink:label="lab_us-gaap_InterestRateFairValueHedgeDerivativeAtFairValueNet_2951E193C448F6C63DF55E3EE74BF8F5" xlink:role="http://www.xbrl.org/2009/role/negatedTerseLabel" xlink:type="resource" xml:lang="en-US"> Interest rate derivative hedge, negative fair value </link:label>
<link:label id="lab_us-gaap_InterestRateFairValueHedgeDerivativeAtFairValueNet_2951E193C448F6C63DF55E3EE74BF8F5_label_en-US" xlink:label="lab_us-gaap_InterestRateFairValueHedgeDerivativeAtFairValueNet_2951E193C448F6C63DF55E3EE74BF8F5" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Interest Rate Fair Value Hedge Derivative at Fair Value, Net </link:label>
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<link:label id="lab_us-gaap_LettersOfCreditOutstandingAmount_83F8FE7F40DA041D71625E3EE74B9755_terseLabel_en-US" xlink:label="lab_us-gaap_LettersOfCreditOutstandingAmount_83F8FE7F40DA041D71625E3EE74B9755" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Letters of credit outstanding </link:label>
<link:label id="lab_us-gaap_LettersOfCreditOutstandingAmount_83F8FE7F40DA041D71625E3EE74B9755_label_en-US" xlink:label="lab_us-gaap_LettersOfCreditOutstandingAmount_83F8FE7F40DA041D71625E3EE74B9755" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Letters of Credit Outstanding, Amount </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_LettersOfCreditOutstandingAmount" xlink:label="loc_us-gaap_LettersOfCreditOutstandingAmount_83F8FE7F40DA041D71625E3EE74B9755" xlink:type="locator"/>
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<link:label id="lab_us-gaap_ReconciliationOfOperatingProfitLossFromSegmentsToConsolidatedTable_71B49608ED9191F19B5EB4CBF205E24A_terseLabel_en-US" xlink:label="lab_us-gaap_ReconciliationOfOperatingProfitLossFromSegmentsToConsolidatedTable_71B49608ED9191F19B5EB4CBF205E24A" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Reconciliation of Operating Profit (Loss) from Segments to Consolidated [Table] </link:label>
<link:label id="lab_us-gaap_ReconciliationOfOperatingProfitLossFromSegmentsToConsolidatedTable_71B49608ED9191F19B5EB4CBF205E24A_label_en-US" xlink:label="lab_us-gaap_ReconciliationOfOperatingProfitLossFromSegmentsToConsolidatedTable_71B49608ED9191F19B5EB4CBF205E24A" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Reconciliation of Operating Profit (Loss) from Segments to Consolidated [Table] </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ReconciliationOfOperatingProfitLossFromSegmentsToConsolidatedTable" xlink:label="loc_us-gaap_ReconciliationOfOperatingProfitLossFromSegmentsToConsolidatedTable_71B49608ED9191F19B5EB4CBF205E24A" xlink:type="locator"/>
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<link:label id="lab_us-gaap_ConsolidationItemsAxis_7B21B348ECBFC3A4E084B4CBF205CB26_terseLabel_en-US" xlink:label="lab_us-gaap_ConsolidationItemsAxis_7B21B348ECBFC3A4E084B4CBF205CB26" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Consolidation Items [Axis] </link:label>
<link:label id="lab_us-gaap_ConsolidationItemsAxis_7B21B348ECBFC3A4E084B4CBF205CB26_label_en-US" xlink:label="lab_us-gaap_ConsolidationItemsAxis_7B21B348ECBFC3A4E084B4CBF205CB26" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Consolidation Items [Axis] </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ConsolidationItemsAxis" xlink:label="loc_us-gaap_ConsolidationItemsAxis_7B21B348ECBFC3A4E084B4CBF205CB26" xlink:type="locator"/>
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<link:label id="lab_us-gaap_ConsolidationItemsDomain_24466D4C458F46927BE5B4CBF205F67D_terseLabel_en-US" xlink:label="lab_us-gaap_ConsolidationItemsDomain_24466D4C458F46927BE5B4CBF205F67D" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Consolidation Items [Domain] </link:label>
<link:label id="lab_us-gaap_ConsolidationItemsDomain_24466D4C458F46927BE5B4CBF205F67D_label_en-US" xlink:label="lab_us-gaap_ConsolidationItemsDomain_24466D4C458F46927BE5B4CBF205F67D" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Consolidation Items [Domain] </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ConsolidationItemsDomain" xlink:label="loc_us-gaap_ConsolidationItemsDomain_24466D4C458F46927BE5B4CBF205F67D" xlink:type="locator"/>
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<link:label id="lab_us-gaap_OperatingSegmentsMember_A7AFD97F0BBE14716ECFB4CBF2055093_terseLabel_en-US" xlink:label="lab_us-gaap_OperatingSegmentsMember_A7AFD97F0BBE14716ECFB4CBF2055093" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Operating Segments </link:label>
<link:label id="lab_us-gaap_OperatingSegmentsMember_A7AFD97F0BBE14716ECFB4CBF2055093_label_en-US" xlink:label="lab_us-gaap_OperatingSegmentsMember_A7AFD97F0BBE14716ECFB4CBF2055093" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Operating Segments [Member] </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_OperatingSegmentsMember" xlink:label="loc_us-gaap_OperatingSegmentsMember_A7AFD97F0BBE14716ECFB4CBF2055093" xlink:type="locator"/>
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<link:label id="lab_it_CorporateAndReconcilingItemsMember_5F149D6690CF54149929B4CBF205956D_terseLabel_en-US" xlink:label="lab_it_CorporateAndReconcilingItemsMember_5F149D6690CF54149929B4CBF205956D" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Corporate and Reconciling Items </link:label>
<link:label id="lab_it_CorporateAndReconcilingItemsMember_5F149D6690CF54149929B4CBF205956D_label_en-US" xlink:label="lab_it_CorporateAndReconcilingItemsMember_5F149D6690CF54149929B4CBF205956D" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Corporate And Reconciling Items [Member] </link:label>
<link:label id="lab_it_CorporateAndReconcilingItemsMember_5F149D6690CF54149929B4CBF205956D_documentation_en-US" xlink:label="lab_it_CorporateAndReconcilingItemsMember_5F149D6690CF54149929B4CBF205956D" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US"> Corporate And Reconciling Items [Member] </link:label>
<link:loc xlink:href="it-20161231.xsd#it_CorporateAndReconcilingItemsMember" xlink:label="loc_it_CorporateAndReconcilingItemsMember_5F149D6690CF54149929B4CBF205956D" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_it_CorporateAndReconcilingItemsMember_5F149D6690CF54149929B4CBF205956D" xlink:to="lab_it_CorporateAndReconcilingItemsMember_5F149D6690CF54149929B4CBF205956D" xlink:type="arc"/>
<link:label id="lab_us-gaap_SegmentReportingReconcilingItemForOperatingProfitLossFromSegmentToConsolidatedLineItems_6E23ED02AD787252AA0BB4CBF20551AA_terseLabel_en-US" xlink:label="lab_us-gaap_SegmentReportingReconcilingItemForOperatingProfitLossFromSegmentToConsolidatedLineItems_6E23ED02AD787252AA0BB4CBF20551AA" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items] </link:label>
<link:label id="lab_us-gaap_SegmentReportingReconcilingItemForOperatingProfitLossFromSegmentToConsolidatedLineItems_6E23ED02AD787252AA0BB4CBF20551AA_label_en-US" xlink:label="lab_us-gaap_SegmentReportingReconcilingItemForOperatingProfitLossFromSegmentToConsolidatedLineItems_6E23ED02AD787252AA0BB4CBF20551AA" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items] </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_SegmentReportingReconcilingItemForOperatingProfitLossFromSegmentToConsolidatedLineItems" xlink:label="loc_us-gaap_SegmentReportingReconcilingItemForOperatingProfitLossFromSegmentToConsolidatedLineItems_6E23ED02AD787252AA0BB4CBF20551AA" xlink:type="locator"/>
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<link:label id="lab_us-gaap_GrossProfit_2BB50F5DD953E86AC3DFB4CBF205CE28_terseLabel_en-US" xlink:label="lab_us-gaap_GrossProfit_2BB50F5DD953E86AC3DFB4CBF205CE28" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Total segment gross contribution </link:label>
<link:label id="lab_us-gaap_GrossProfit_2BB50F5DD953E86AC3DFB4CBF205CE28_label_en-US" xlink:label="lab_us-gaap_GrossProfit_2BB50F5DD953E86AC3DFB4CBF205CE28" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Gross Profit </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_GrossProfit" xlink:label="loc_us-gaap_GrossProfit_2BB50F5DD953E86AC3DFB4CBF205CE28" xlink:type="locator"/>
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<link:label id="lab_us-gaap_CostsAndExpensesAbstract_9980228E6CFBEC41E429B4CBF2058B17_verboseLabel_en-US" xlink:label="lab_us-gaap_CostsAndExpensesAbstract_9980228E6CFBEC41E429B4CBF2058B17" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:type="resource" xml:lang="en-US"> Costs and expenses: </link:label>
<link:label id="lab_us-gaap_CostsAndExpensesAbstract_9980228E6CFBEC41E429B4CBF2058B17_label_en-US" xlink:label="lab_us-gaap_CostsAndExpensesAbstract_9980228E6CFBEC41E429B4CBF2058B17" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Costs and Expenses [Abstract] </link:label>
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<link:label id="lab_us-gaap_CostOfServices_0BA9FD2A81E4E0217701B4CBF2064E10_terseLabel_en-US" xlink:label="lab_us-gaap_CostOfServices_0BA9FD2A81E4E0217701B4CBF2064E10" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Cost of services and product development </link:label>
<link:label id="lab_us-gaap_CostOfServices_0BA9FD2A81E4E0217701B4CBF2064E10_label_en-US" xlink:label="lab_us-gaap_CostOfServices_0BA9FD2A81E4E0217701B4CBF2064E10" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Cost of Services </link:label>
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<link:label id="lab_us-gaap_SellingGeneralAndAdministrativeExpense_4A84A0FF74A5B3EAA4FFB4CBF206A84A_label_en-US" xlink:label="lab_us-gaap_SellingGeneralAndAdministrativeExpense_4A84A0FF74A5B3EAA4FFB4CBF206A84A" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Selling, General and Administrative Expense </link:label>
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<link:label id="lab_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearThree_4156633E970DDE2B0A243E9436DCAE02_terseLabel_en-US" xlink:label="lab_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearThree_4156633E970DDE2B0A243E9436DCAE02" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> 2019 </link:label>
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<link:label id="lab_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFour_5589506A65B60D24FC4D3E9436DCD8F5_terseLabel_en-US" xlink:label="lab_us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFour_5589506A65B60D24FC4D3E9436DCD8F5" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> 2020 </link:label>
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<link:label id="lab_it_BenefitExpenseRelatingToDefinedBenefitPensionAdjustmentsUsedToIncreaseDecreaseEquityMember_E7B38012243A09B3D14DB3EBB0182788_terseLabel_en-US" xlink:label="lab_it_BenefitExpenseRelatingToDefinedBenefitPensionAdjustmentsUsedToIncreaseDecreaseEquityMember_E7B38012243A09B3D14DB3EBB0182788" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Benefit (expense) relating to defined-benefit pension adjustments used to increase (decrease) equity </link:label>
<link:label id="lab_it_BenefitExpenseRelatingToDefinedBenefitPensionAdjustmentsUsedToIncreaseDecreaseEquityMember_E7B38012243A09B3D14DB3EBB0182788_label_en-US" xlink:label="lab_it_BenefitExpenseRelatingToDefinedBenefitPensionAdjustmentsUsedToIncreaseDecreaseEquityMember_E7B38012243A09B3D14DB3EBB0182788" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Benefit Expense Relating To Defined Benefit Pension Adjustments Used To Increase Decrease Equity [Member] </link:label>
<link:label id="lab_it_BenefitExpenseRelatingToDefinedBenefitPensionAdjustmentsUsedToIncreaseDecreaseEquityMember_E7B38012243A09B3D14DB3EBB0182788_documentation_en-US" xlink:label="lab_it_BenefitExpenseRelatingToDefinedBenefitPensionAdjustmentsUsedToIncreaseDecreaseEquityMember_E7B38012243A09B3D14DB3EBB0182788" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US"> -- None. No documentation exists for this element. -- </link:label>
<link:loc xlink:href="it-20161231.xsd#it_BenefitExpenseRelatingToDefinedBenefitPensionAdjustmentsUsedToIncreaseDecreaseEquityMember" xlink:label="loc_it_BenefitExpenseRelatingToDefinedBenefitPensionAdjustmentsUsedToIncreaseDecreaseEquityMember_E7B38012243A09B3D14DB3EBB0182788" xlink:type="locator"/>
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<link:label id="lab_it_CurrentTaxExpenseAbstract_146444BD46F520AC5117B3EBB018EDD0_terseLabel_en-US" xlink:label="lab_it_CurrentTaxExpenseAbstract_146444BD46F520AC5117B3EBB018EDD0" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Current tax expense: </link:label>
<link:label id="lab_it_CurrentTaxExpenseAbstract_146444BD46F520AC5117B3EBB018EDD0_label_en-US" xlink:label="lab_it_CurrentTaxExpenseAbstract_146444BD46F520AC5117B3EBB018EDD0" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Current tax expense: [Abstract] </link:label>
<link:label id="lab_it_CurrentTaxExpenseAbstract_146444BD46F520AC5117B3EBB018EDD0_documentation_en-US" xlink:label="lab_it_CurrentTaxExpenseAbstract_146444BD46F520AC5117B3EBB018EDD0" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US"> -- None. No documentation exists for this element. -- </link:label>
<link:loc xlink:href="it-20161231.xsd#it_CurrentTaxExpenseAbstract" xlink:label="loc_it_CurrentTaxExpenseAbstract_146444BD46F520AC5117B3EBB018EDD0" xlink:type="locator"/>
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<link:label id="lab_us-gaap_CurrentFederalTaxExpenseBenefit_7E7FAC082C00E1D59818B3EBB0185CD9_terseLabel_en-US" xlink:label="lab_us-gaap_CurrentFederalTaxExpenseBenefit_7E7FAC082C00E1D59818B3EBB0185CD9" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> U.S. federal </link:label>
<link:label id="lab_us-gaap_CurrentFederalTaxExpenseBenefit_7E7FAC082C00E1D59818B3EBB0185CD9_label_en-US" xlink:label="lab_us-gaap_CurrentFederalTaxExpenseBenefit_7E7FAC082C00E1D59818B3EBB0185CD9" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Current Federal Tax Expense (Benefit) </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_CurrentFederalTaxExpenseBenefit" xlink:label="loc_us-gaap_CurrentFederalTaxExpenseBenefit_7E7FAC082C00E1D59818B3EBB0185CD9" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_CurrentFederalTaxExpenseBenefit_7E7FAC082C00E1D59818B3EBB0185CD9" xlink:to="lab_us-gaap_CurrentFederalTaxExpenseBenefit_7E7FAC082C00E1D59818B3EBB0185CD9" xlink:type="arc"/>
<link:label id="lab_us-gaap_CurrentStateAndLocalTaxExpenseBenefit_9436289AD267F6A36BDFB3EBB018CBF9_terseLabel_en-US" xlink:label="lab_us-gaap_CurrentStateAndLocalTaxExpenseBenefit_9436289AD267F6A36BDFB3EBB018CBF9" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> State and local </link:label>
<link:label id="lab_us-gaap_CurrentStateAndLocalTaxExpenseBenefit_9436289AD267F6A36BDFB3EBB018CBF9_label_en-US" xlink:label="lab_us-gaap_CurrentStateAndLocalTaxExpenseBenefit_9436289AD267F6A36BDFB3EBB018CBF9" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Current State and Local Tax Expense (Benefit) </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_CurrentStateAndLocalTaxExpenseBenefit" xlink:label="loc_us-gaap_CurrentStateAndLocalTaxExpenseBenefit_9436289AD267F6A36BDFB3EBB018CBF9" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_CurrentStateAndLocalTaxExpenseBenefit_9436289AD267F6A36BDFB3EBB018CBF9" xlink:to="lab_us-gaap_CurrentStateAndLocalTaxExpenseBenefit_9436289AD267F6A36BDFB3EBB018CBF9" xlink:type="arc"/>
<link:label id="lab_us-gaap_CurrentForeignTaxExpenseBenefit_7D5FFD50723D244D3D0BB3EBB01842E2_terseLabel_en-US" xlink:label="lab_us-gaap_CurrentForeignTaxExpenseBenefit_7D5FFD50723D244D3D0BB3EBB01842E2" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Foreign </link:label>
<link:label id="lab_us-gaap_CurrentForeignTaxExpenseBenefit_7D5FFD50723D244D3D0BB3EBB01842E2_label_en-US" xlink:label="lab_us-gaap_CurrentForeignTaxExpenseBenefit_7D5FFD50723D244D3D0BB3EBB01842E2" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Current Foreign Tax Expense (Benefit) </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_CurrentForeignTaxExpenseBenefit" xlink:label="loc_us-gaap_CurrentForeignTaxExpenseBenefit_7D5FFD50723D244D3D0BB3EBB01842E2" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_CurrentForeignTaxExpenseBenefit_7D5FFD50723D244D3D0BB3EBB01842E2" xlink:to="lab_us-gaap_CurrentForeignTaxExpenseBenefit_7D5FFD50723D244D3D0BB3EBB01842E2" xlink:type="arc"/>
<link:label id="lab_us-gaap_CurrentIncomeTaxExpenseBenefit_ECEEB452069574590918B3EBB0188F31_totalLabel_en-US" xlink:label="lab_us-gaap_CurrentIncomeTaxExpenseBenefit_ECEEB452069574590918B3EBB0188F31" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:type="resource" xml:lang="en-US"> Total current </link:label>
<link:label id="lab_us-gaap_CurrentIncomeTaxExpenseBenefit_ECEEB452069574590918B3EBB0188F31_label_en-US" xlink:label="lab_us-gaap_CurrentIncomeTaxExpenseBenefit_ECEEB452069574590918B3EBB0188F31" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Current Income Tax Expense (Benefit) </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_CurrentIncomeTaxExpenseBenefit" xlink:label="loc_us-gaap_CurrentIncomeTaxExpenseBenefit_ECEEB452069574590918B3EBB0188F31" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_CurrentIncomeTaxExpenseBenefit_ECEEB452069574590918B3EBB0188F31" xlink:to="lab_us-gaap_CurrentIncomeTaxExpenseBenefit_ECEEB452069574590918B3EBB0188F31" xlink:type="arc"/>
<link:label id="lab_it_DeferredTaxBenefitExpenseAbstract_F083DF04212239EE57FAB3EBB0189874_terseLabel_en-US" xlink:label="lab_it_DeferredTaxBenefitExpenseAbstract_F083DF04212239EE57FAB3EBB0189874" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Deferred tax (benefit) expense: </link:label>
<link:label id="lab_it_DeferredTaxBenefitExpenseAbstract_F083DF04212239EE57FAB3EBB0189874_label_en-US" xlink:label="lab_it_DeferredTaxBenefitExpenseAbstract_F083DF04212239EE57FAB3EBB0189874" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Deferred tax (benefit) expense: [Abstract] </link:label>
<link:label id="lab_it_DeferredTaxBenefitExpenseAbstract_F083DF04212239EE57FAB3EBB0189874_documentation_en-US" xlink:label="lab_it_DeferredTaxBenefitExpenseAbstract_F083DF04212239EE57FAB3EBB0189874" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US"> -- None. No documentation exists for this element. -- </link:label>
<link:loc xlink:href="it-20161231.xsd#it_DeferredTaxBenefitExpenseAbstract" xlink:label="loc_it_DeferredTaxBenefitExpenseAbstract_F083DF04212239EE57FAB3EBB0189874" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_it_DeferredTaxBenefitExpenseAbstract_F083DF04212239EE57FAB3EBB0189874" xlink:to="lab_it_DeferredTaxBenefitExpenseAbstract_F083DF04212239EE57FAB3EBB0189874" xlink:type="arc"/>
<link:label id="lab_us-gaap_DeferredFederalIncomeTaxExpenseBenefit_BF29C84E53F78157EA3AB3EBB018DDE3_terseLabel_en-US" xlink:label="lab_us-gaap_DeferredFederalIncomeTaxExpenseBenefit_BF29C84E53F78157EA3AB3EBB018DDE3" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> U.S. federal </link:label>
<link:label id="lab_us-gaap_DeferredFederalIncomeTaxExpenseBenefit_BF29C84E53F78157EA3AB3EBB018DDE3_label_en-US" xlink:label="lab_us-gaap_DeferredFederalIncomeTaxExpenseBenefit_BF29C84E53F78157EA3AB3EBB018DDE3" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Deferred Federal Income Tax Expense (Benefit) </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_DeferredFederalIncomeTaxExpenseBenefit" xlink:label="loc_us-gaap_DeferredFederalIncomeTaxExpenseBenefit_BF29C84E53F78157EA3AB3EBB018DDE3" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DeferredFederalIncomeTaxExpenseBenefit_BF29C84E53F78157EA3AB3EBB018DDE3" xlink:to="lab_us-gaap_DeferredFederalIncomeTaxExpenseBenefit_BF29C84E53F78157EA3AB3EBB018DDE3" xlink:type="arc"/>
<link:label id="lab_us-gaap_DeferredStateAndLocalIncomeTaxExpenseBenefit_85192D2994BE4D12D0FFB3EBB018EA97_terseLabel_en-US" xlink:label="lab_us-gaap_DeferredStateAndLocalIncomeTaxExpenseBenefit_85192D2994BE4D12D0FFB3EBB018EA97" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> State and local </link:label>
<link:label id="lab_us-gaap_DeferredStateAndLocalIncomeTaxExpenseBenefit_85192D2994BE4D12D0FFB3EBB018EA97_label_en-US" xlink:label="lab_us-gaap_DeferredStateAndLocalIncomeTaxExpenseBenefit_85192D2994BE4D12D0FFB3EBB018EA97" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Deferred State and Local Income Tax Expense (Benefit) </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_DeferredStateAndLocalIncomeTaxExpenseBenefit" xlink:label="loc_us-gaap_DeferredStateAndLocalIncomeTaxExpenseBenefit_85192D2994BE4D12D0FFB3EBB018EA97" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DeferredStateAndLocalIncomeTaxExpenseBenefit_85192D2994BE4D12D0FFB3EBB018EA97" xlink:to="lab_us-gaap_DeferredStateAndLocalIncomeTaxExpenseBenefit_85192D2994BE4D12D0FFB3EBB018EA97" xlink:type="arc"/>
<link:label id="lab_us-gaap_DeferredForeignIncomeTaxExpenseBenefit_C320832456C0F5023822B3EBB01814D2_terseLabel_en-US" xlink:label="lab_us-gaap_DeferredForeignIncomeTaxExpenseBenefit_C320832456C0F5023822B3EBB01814D2" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Foreign </link:label>
<link:label id="lab_us-gaap_DeferredForeignIncomeTaxExpenseBenefit_C320832456C0F5023822B3EBB01814D2_label_en-US" xlink:label="lab_us-gaap_DeferredForeignIncomeTaxExpenseBenefit_C320832456C0F5023822B3EBB01814D2" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Deferred Foreign Income Tax Expense (Benefit) </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_DeferredForeignIncomeTaxExpenseBenefit" xlink:label="loc_us-gaap_DeferredForeignIncomeTaxExpenseBenefit_C320832456C0F5023822B3EBB01814D2" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DeferredForeignIncomeTaxExpenseBenefit_C320832456C0F5023822B3EBB01814D2" xlink:to="lab_us-gaap_DeferredForeignIncomeTaxExpenseBenefit_C320832456C0F5023822B3EBB01814D2" xlink:type="arc"/>
<link:label id="lab_us-gaap_DeferredIncomeTaxExpenseBenefit_F69F0392E113E6A1FF7CB3EBB01947D4_totalLabel_en-US" xlink:label="lab_us-gaap_DeferredIncomeTaxExpenseBenefit_F69F0392E113E6A1FF7CB3EBB01947D4" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:type="resource" xml:lang="en-US"> Total deferred </link:label>
<link:label id="lab_us-gaap_DeferredIncomeTaxExpenseBenefit_F69F0392E113E6A1FF7CB3EBB01947D4_label_en-US" xlink:label="lab_us-gaap_DeferredIncomeTaxExpenseBenefit_F69F0392E113E6A1FF7CB3EBB01947D4" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Deferred Income Tax Expense (Benefit) </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_DeferredIncomeTaxExpenseBenefit" xlink:label="loc_us-gaap_DeferredIncomeTaxExpenseBenefit_F69F0392E113E6A1FF7CB3EBB01947D4" xlink:type="locator"/>
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<link:label id="lab_it_IncomeTaxExpenseBenefitbeforeOther_D00D44759369E10F6CEFB3EBB019D78B_totalLabel_en-US" xlink:label="lab_it_IncomeTaxExpenseBenefitbeforeOther_D00D44759369E10F6CEFB3EBB019D78B" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:type="resource" xml:lang="en-US"> Total current and deferred </link:label>
<link:label id="lab_it_IncomeTaxExpenseBenefitbeforeOther_D00D44759369E10F6CEFB3EBB019D78B_label_en-US" xlink:label="lab_it_IncomeTaxExpenseBenefitbeforeOther_D00D44759369E10F6CEFB3EBB019D78B" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Income Tax Expense (Benefit) before Other </link:label>
<link:label id="lab_it_IncomeTaxExpenseBenefitbeforeOther_D00D44759369E10F6CEFB3EBB019D78B_documentation_en-US" xlink:label="lab_it_IncomeTaxExpenseBenefitbeforeOther_D00D44759369E10F6CEFB3EBB019D78B" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US"> Income Tax Expense (Benefit) before Other </link:label>
<link:loc xlink:href="it-20161231.xsd#it_IncomeTaxExpenseBenefitbeforeOther" xlink:label="loc_it_IncomeTaxExpenseBenefitbeforeOther_D00D44759369E10F6CEFB3EBB019D78B" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_it_IncomeTaxExpenseBenefitbeforeOther_D00D44759369E10F6CEFB3EBB019D78B" xlink:to="lab_it_IncomeTaxExpenseBenefitbeforeOther_D00D44759369E10F6CEFB3EBB019D78B" xlink:type="arc"/>
<link:label id="lab_us-gaap_OtherTaxExpenseBenefit_1770DD75FE4C6F7BDD38B3EBB0199EBD_terseLabel_en-US" xlink:label="lab_us-gaap_OtherTaxExpenseBenefit_1770DD75FE4C6F7BDD38B3EBB0199EBD" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Other tax benefit (expense) </link:label>
<link:label id="lab_us-gaap_OtherTaxExpenseBenefit_1770DD75FE4C6F7BDD38B3EBB0199EBD_label_en-US" xlink:label="lab_us-gaap_OtherTaxExpenseBenefit_1770DD75FE4C6F7BDD38B3EBB0199EBD" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Other Tax Expense (Benefit) </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_OtherTaxExpenseBenefit" xlink:label="loc_us-gaap_OtherTaxExpenseBenefit_1770DD75FE4C6F7BDD38B3EBB0199EBD" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_OtherTaxExpenseBenefit_1770DD75FE4C6F7BDD38B3EBB0199EBD" xlink:to="lab_us-gaap_OtherTaxExpenseBenefit_1770DD75FE4C6F7BDD38B3EBB0199EBD" xlink:type="arc"/>
<link:label id="lab_us-gaap_IncomeTaxExpenseBenefit_AEAD0A4E7A44007799D5B3EBB019AEBB_totalLabel_en-US" xlink:label="lab_us-gaap_IncomeTaxExpenseBenefit_AEAD0A4E7A44007799D5B3EBB019AEBB" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:type="resource" xml:lang="en-US"> Total tax expense </link:label>
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<link:label id="lab_us-gaap_ScheduleOfNetBenefitCostsTableTextBlock_EEFBB8F6458DEE07CF88E53BFB8A139B_terseLabel_en-US" xlink:label="lab_us-gaap_ScheduleOfNetBenefitCostsTableTextBlock_EEFBB8F6458DEE07CF88E53BFB8A139B" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Schedule of Components of Defined Benefit Pension Expense </link:label>
<link:label id="lab_us-gaap_ScheduleOfNetBenefitCostsTableTextBlock_EEFBB8F6458DEE07CF88E53BFB8A139B_label_en-US" xlink:label="lab_us-gaap_ScheduleOfNetBenefitCostsTableTextBlock_EEFBB8F6458DEE07CF88E53BFB8A139B" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Schedule of Net Benefit Costs [Table Text Block] </link:label>
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<link:label id="lab_us-gaap_ScheduleOfNetPeriodicBenefitCostNotYetRecognizedTableTextBlock_2391551E478ED8A2F1E1E53BFB8A42FC_terseLabel_en-US" xlink:label="lab_us-gaap_ScheduleOfNetPeriodicBenefitCostNotYetRecognizedTableTextBlock_2391551E478ED8A2F1E1E53BFB8A42FC" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Schedule of Assumptions Used in the Computation of Pension Expense </link:label>
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<link:label id="lab_us-gaap_ScheduleOfChangesInProjectedBenefitObligationsTableTextBlock_0DD5D0B925562EDB1E4DE53BFB8AC017_terseLabel_en-US" xlink:label="lab_us-gaap_ScheduleOfChangesInProjectedBenefitObligationsTableTextBlock_0DD5D0B925562EDB1E4DE53BFB8AC017" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Schedule of Changes in the Projected Benefit Obligation </link:label>
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<link:label id="lab_us-gaap_ScheduleOfAmountsRecognizedInBalanceSheetTableTextBlock_26CC9F4594F3952EC4C4E53BFB8A5C52_terseLabel_en-US" xlink:label="lab_us-gaap_ScheduleOfAmountsRecognizedInBalanceSheetTableTextBlock_26CC9F4594F3952EC4C4E53BFB8A5C52" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Schedule of Funded Status of the Plans and Related Amounts Recorded in Consolidated Balance Sheet </link:label>
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<link:label id="lab_us-gaap_DebtDisclosureTextBlock_0AEBE9939C0D2BF262924797E139DBBB_terseLabel_en-US" xlink:label="lab_us-gaap_DebtDisclosureTextBlock_0AEBE9939C0D2BF262924797E139DBBB" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> DEBT </link:label>
<link:label id="lab_us-gaap_DebtDisclosureTextBlock_0AEBE9939C0D2BF262924797E139DBBB_label_en-US" xlink:label="lab_us-gaap_DebtDisclosureTextBlock_0AEBE9939C0D2BF262924797E139DBBB" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Debt Disclosure [Text Block] </link:label>
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<link:label id="lab_it_BorrowingsFairValueDisclosure_33A23B36754918C90C55E53BFD71937D_terseLabel_en-US" xlink:label="lab_it_BorrowingsFairValueDisclosure_33A23B36754918C90C55E53BFD71937D" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Borrowings, fair value disclosure </link:label>
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<link:label id="lab_us-gaap_EmployeeRelatedLiabilitiesCurrent_1B1DEC40994E957DB5953ED1D6B18B9E_terseLabel_en-US" xlink:label="lab_us-gaap_EmployeeRelatedLiabilitiesCurrent_1B1DEC40994E957DB5953ED1D6B18B9E" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Payroll and employee benefits payable </link:label>
<link:label id="lab_us-gaap_EmployeeRelatedLiabilitiesCurrent_1B1DEC40994E957DB5953ED1D6B18B9E_label_en-US" xlink:label="lab_us-gaap_EmployeeRelatedLiabilitiesCurrent_1B1DEC40994E957DB5953ED1D6B18B9E" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Employee-related Liabilities, Current </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_EmployeeRelatedLiabilitiesCurrent" xlink:label="loc_us-gaap_EmployeeRelatedLiabilitiesCurrent_1B1DEC40994E957DB5953ED1D6B18B9E" xlink:type="locator"/>
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<link:label id="lab_it_SeveranceandRetentionBonusPayable_E34806BC7915A8E492AD3ED1D6B12F05_terseLabel_en-US" xlink:label="lab_it_SeveranceandRetentionBonusPayable_E34806BC7915A8E492AD3ED1D6B12F05" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Severance and retention bonus payable </link:label>
<link:label id="lab_it_SeveranceandRetentionBonusPayable_E34806BC7915A8E492AD3ED1D6B12F05_label_en-US" xlink:label="lab_it_SeveranceandRetentionBonusPayable_E34806BC7915A8E492AD3ED1D6B12F05" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Severance and Retention Bonus Payable </link:label>
<link:label id="lab_it_SeveranceandRetentionBonusPayable_E34806BC7915A8E492AD3ED1D6B12F05_documentation_en-US" xlink:label="lab_it_SeveranceandRetentionBonusPayable_E34806BC7915A8E492AD3ED1D6B12F05" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US"> Severance and Retention Bonus Payable </link:label>
<link:loc xlink:href="it-20161231.xsd#it_SeveranceandRetentionBonusPayable" xlink:label="loc_it_SeveranceandRetentionBonusPayable_E34806BC7915A8E492AD3ED1D6B12F05" xlink:type="locator"/>
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<link:label id="lab_us-gaap_AccruedBonusesCurrent_048EE1F7A637E49FF9613ED1D6B13261_terseLabel_en-US" xlink:label="lab_us-gaap_AccruedBonusesCurrent_048EE1F7A637E49FF9613ED1D6B13261" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Bonus payable </link:label>
<link:label id="lab_us-gaap_AccruedBonusesCurrent_048EE1F7A637E49FF9613ED1D6B13261_label_en-US" xlink:label="lab_us-gaap_AccruedBonusesCurrent_048EE1F7A637E49FF9613ED1D6B13261" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Accrued Bonuses, Current </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_AccruedBonusesCurrent" xlink:label="loc_us-gaap_AccruedBonusesCurrent_048EE1F7A637E49FF9613ED1D6B13261" xlink:type="locator"/>
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<link:label id="lab_us-gaap_AccruedSalesCommissionCurrent_E8BC40CD16F0E140C21D3ED1D6B26AC0_terseLabel_en-US" xlink:label="lab_us-gaap_AccruedSalesCommissionCurrent_E8BC40CD16F0E140C21D3ED1D6B26AC0" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Commissions payable </link:label>
<link:label id="lab_us-gaap_AccruedSalesCommissionCurrent_E8BC40CD16F0E140C21D3ED1D6B26AC0_label_en-US" xlink:label="lab_us-gaap_AccruedSalesCommissionCurrent_E8BC40CD16F0E140C21D3ED1D6B26AC0" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Accrued Sales Commission, Current </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_AccruedSalesCommissionCurrent" xlink:label="loc_us-gaap_AccruedSalesCommissionCurrent_E8BC40CD16F0E140C21D3ED1D6B26AC0" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_AccruedSalesCommissionCurrent_E8BC40CD16F0E140C21D3ED1D6B26AC0" xlink:to="lab_us-gaap_AccruedSalesCommissionCurrent_E8BC40CD16F0E140C21D3ED1D6B26AC0" xlink:type="arc"/>
<link:label id="lab_us-gaap_TaxesPayableCurrent_EE88AEAA401803BDA0A93ED1D6B28D73_terseLabel_en-US" xlink:label="lab_us-gaap_TaxesPayableCurrent_EE88AEAA401803BDA0A93ED1D6B28D73" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Taxes payable </link:label>
<link:label id="lab_us-gaap_TaxesPayableCurrent_EE88AEAA401803BDA0A93ED1D6B28D73_label_en-US" xlink:label="lab_us-gaap_TaxesPayableCurrent_EE88AEAA401803BDA0A93ED1D6B28D73" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Taxes Payable, Current </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_TaxesPayableCurrent" xlink:label="loc_us-gaap_TaxesPayableCurrent_EE88AEAA401803BDA0A93ED1D6B28D73" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_TaxesPayableCurrent_EE88AEAA401803BDA0A93ED1D6B28D73" xlink:to="lab_us-gaap_TaxesPayableCurrent_EE88AEAA401803BDA0A93ED1D6B28D73" xlink:type="arc"/>
<link:label id="lab_us-gaap_OtherAccruedLiabilitiesCurrent_75ACEDE1D76C9B6624FD3ED1D6B290E1_terseLabel_en-US" xlink:label="lab_us-gaap_OtherAccruedLiabilitiesCurrent_75ACEDE1D76C9B6624FD3ED1D6B290E1" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Other accrued liabilities </link:label>
<link:label id="lab_us-gaap_OtherAccruedLiabilitiesCurrent_75ACEDE1D76C9B6624FD3ED1D6B290E1_label_en-US" xlink:label="lab_us-gaap_OtherAccruedLiabilitiesCurrent_75ACEDE1D76C9B6624FD3ED1D6B290E1" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Other Accrued Liabilities, Current </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_OtherAccruedLiabilitiesCurrent" xlink:label="loc_us-gaap_OtherAccruedLiabilitiesCurrent_75ACEDE1D76C9B6624FD3ED1D6B290E1" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_OtherAccruedLiabilitiesCurrent_75ACEDE1D76C9B6624FD3ED1D6B290E1" xlink:to="lab_us-gaap_OtherAccruedLiabilitiesCurrent_75ACEDE1D76C9B6624FD3ED1D6B290E1" xlink:type="arc"/>
<link:label id="lab_us-gaap_AccountsPayableAndAccruedLiabilitiesCurrent_0803D9FBF7186C17C0633ED1D6B214F0_totalLabel_en-US" xlink:label="lab_us-gaap_AccountsPayableAndAccruedLiabilitiesCurrent_0803D9FBF7186C17C0633ED1D6B214F0" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:type="resource" xml:lang="en-US"> Total accounts payable and accrued liabilities </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_AccountsPayableAndAccruedLiabilitiesCurrent" xlink:label="loc_us-gaap_AccountsPayableAndAccruedLiabilitiesCurrent_0803D9FBF7186C17C0633ED1D6B214F0" xlink:type="locator"/>
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<link:label id="lab_us-gaap_DefinedBenefitPlanBenefitObligation_114284734B991829F41E3F57B215C6CC_terseLabel_en-US" xlink:label="lab_us-gaap_DefinedBenefitPlanBenefitObligation_114284734B991829F41E3F57B215C6CC" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Projected benefit obligation </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_DefinedBenefitPlanBenefitObligation" xlink:label="loc_us-gaap_DefinedBenefitPlanBenefitObligation_114284734B991829F41E3F57B215C6CC" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_DefinedBenefitPlanBenefitObligation_114284734B991829F41E3F57B215C6CC" xlink:to="lab_us-gaap_DefinedBenefitPlanBenefitObligation_114284734B991829F41E3F57B215C6CC" xlink:type="arc"/>
<link:label id="lab_us-gaap_DefinedBenefitPlanPensionPlansWithAccumulatedBenefitObligationsInExcessOfPlanAssetsAggregateFairValueOfPlanAssets_C0DCBA9B184348CAD2653F57B215AE64_negatedTerseLabel_en-US" xlink:label="lab_us-gaap_DefinedBenefitPlanPensionPlansWithAccumulatedBenefitObligationsInExcessOfPlanAssetsAggregateFairValueOfPlanAssets_C0DCBA9B184348CAD2653F57B215AE64" xlink:role="http://www.xbrl.org/2009/role/negatedTerseLabel" xlink:type="resource" xml:lang="en-US"> Pension plan assets at fair value </link:label>
<link:label id="lab_us-gaap_DefinedBenefitPlanPensionPlansWithAccumulatedBenefitObligationsInExcessOfPlanAssetsAggregateFairValueOfPlanAssets_C0DCBA9B184348CAD2653F57B215AE64_label_en-US" xlink:label="lab_us-gaap_DefinedBenefitPlanPensionPlansWithAccumulatedBenefitObligationsInExcessOfPlanAssetsAggregateFairValueOfPlanAssets_C0DCBA9B184348CAD2653F57B215AE64" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Defined Benefit Plan, Pension Plans with Accumulated Benefit Obligations in Excess of Plan Assets, Aggregate Fair Value of Plan Assets </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_DefinedBenefitPlanPensionPlansWithAccumulatedBenefitObligationsInExcessOfPlanAssetsAggregateFairValueOfPlanAssets" xlink:label="loc_us-gaap_DefinedBenefitPlanPensionPlansWithAccumulatedBenefitObligationsInExcessOfPlanAssetsAggregateFairValueOfPlanAssets_C0DCBA9B184348CAD2653F57B215AE64" xlink:type="locator"/>
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<link:label id="lab_us-gaap_DefinedBenefitPlanPensionPlansWithAccumulatedBenefitObligationsInExcessOfPlanAssetsAggregateProjectedBenefitObligation_E632C96196B01295036D3F57B2165A00_totalLabel_en-US" xlink:label="lab_us-gaap_DefinedBenefitPlanPensionPlansWithAccumulatedBenefitObligationsInExcessOfPlanAssetsAggregateProjectedBenefitObligation_E632C96196B01295036D3F57B2165A00" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:type="resource" xml:lang="en-US"> Funded status – shortfall </link:label>
<link:label id="lab_us-gaap_DefinedBenefitPlanPensionPlansWithAccumulatedBenefitObligationsInExcessOfPlanAssetsAggregateProjectedBenefitObligation_E632C96196B01295036D3F57B2165A00_label_en-US" xlink:label="lab_us-gaap_DefinedBenefitPlanPensionPlansWithAccumulatedBenefitObligationsInExcessOfPlanAssetsAggregateProjectedBenefitObligation_E632C96196B01295036D3F57B2165A00" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Defined Benefit Plan, Pension Plans with Accumulated Benefit Obligations in Excess of Plan Assets, Aggregate Projected Benefit Obligation </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_DefinedBenefitPlanPensionPlansWithAccumulatedBenefitObligationsInExcessOfPlanAssetsAggregateProjectedBenefitObligation" xlink:label="loc_us-gaap_DefinedBenefitPlanPensionPlansWithAccumulatedBenefitObligationsInExcessOfPlanAssetsAggregateProjectedBenefitObligation_E632C96196B01295036D3F57B2165A00" xlink:type="locator"/>
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<link:label id="lab_it_AmountsRecordedInTheConsolidatedBalanceSheetsForThePlansAbstract_5B916F4E8EC6DDA3594F3F57B216AE28_terseLabel_en-US" xlink:label="lab_it_AmountsRecordedInTheConsolidatedBalanceSheetsForThePlansAbstract_5B916F4E8EC6DDA3594F3F57B216AE28" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Amounts recorded in the Consolidated Balance Sheets for the plans: </link:label>
<link:label id="lab_it_AmountsRecordedInTheConsolidatedBalanceSheetsForThePlansAbstract_5B916F4E8EC6DDA3594F3F57B216AE28_label_en-US" xlink:label="lab_it_AmountsRecordedInTheConsolidatedBalanceSheetsForThePlansAbstract_5B916F4E8EC6DDA3594F3F57B216AE28" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Amounts recorded in the Consolidated Balance Sheets for the plans: [Abstract] </link:label>
<link:label id="lab_it_AmountsRecordedInTheConsolidatedBalanceSheetsForThePlansAbstract_5B916F4E8EC6DDA3594F3F57B216AE28_documentation_en-US" xlink:label="lab_it_AmountsRecordedInTheConsolidatedBalanceSheetsForThePlansAbstract_5B916F4E8EC6DDA3594F3F57B216AE28" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US"> -- None. No documentation exists for this element. -- </link:label>
<link:loc xlink:href="it-20161231.xsd#it_AmountsRecordedInTheConsolidatedBalanceSheetsForThePlansAbstract" xlink:label="loc_it_AmountsRecordedInTheConsolidatedBalanceSheetsForThePlansAbstract_5B916F4E8EC6DDA3594F3F57B216AE28" xlink:type="locator"/>
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<link:label id="lab_us-gaap_DefinedBenefitPlanAmountsRecognizedInBalanceSheet_B4724B371E1A4CCB39F73F57B216C019_terseLabel_en-US" xlink:label="lab_us-gaap_DefinedBenefitPlanAmountsRecognizedInBalanceSheet_B4724B371E1A4CCB39F73F57B216C019" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Other liabilities — accrued pension obligation </link:label>
<link:label id="lab_us-gaap_DefinedBenefitPlanAmountsRecognizedInBalanceSheet_B4724B371E1A4CCB39F73F57B216C019_label_en-US" xlink:label="lab_us-gaap_DefinedBenefitPlanAmountsRecognizedInBalanceSheet_B4724B371E1A4CCB39F73F57B216C019" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Defined Benefit Plan, Amounts Recognized in Balance Sheet </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_DefinedBenefitPlanAmountsRecognizedInBalanceSheet" xlink:label="loc_us-gaap_DefinedBenefitPlanAmountsRecognizedInBalanceSheet_B4724B371E1A4CCB39F73F57B216C019" xlink:type="locator"/>
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<link:label id="lab_us-gaap_AccumulatedOtherComprehensiveIncomeLossDefinedBenefitPensionAndOtherPostretirementPlansNetOfTax_5612353BBF0019CA13FC3F57B2167098_verboseLabel_en-US" xlink:label="lab_us-gaap_AccumulatedOtherComprehensiveIncomeLossDefinedBenefitPensionAndOtherPostretirementPlansNetOfTax_5612353BBF0019CA13FC3F57B2167098" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:type="resource" xml:lang="en-US"> Stockholders’ equity — deferred actuarial loss </link:label>
<link:label id="lab_us-gaap_AccumulatedOtherComprehensiveIncomeLossDefinedBenefitPensionAndOtherPostretirementPlansNetOfTax_5612353BBF0019CA13FC3F57B2167098_label_en-US" xlink:label="lab_us-gaap_AccumulatedOtherComprehensiveIncomeLossDefinedBenefitPensionAndOtherPostretirementPlansNetOfTax_5612353BBF0019CA13FC3F57B2167098" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Accumulated Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Net of Tax </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossDefinedBenefitPensionAndOtherPostretirementPlansNetOfTax" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossDefinedBenefitPensionAndOtherPostretirementPlansNetOfTax_5612353BBF0019CA13FC3F57B2167098" xlink:type="locator"/>
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<link:label id="lab_us-gaap_SubsequentEventsTextBlock_A0DD90C0CAFF638570E93F8292784E19_terseLabel_en-US" xlink:label="lab_us-gaap_SubsequentEventsTextBlock_A0DD90C0CAFF638570E93F8292784E19" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> SUBSEQUENT EVENTS </link:label>
<link:label id="lab_us-gaap_SubsequentEventsTextBlock_A0DD90C0CAFF638570E93F8292784E19_label_en-US" xlink:label="lab_us-gaap_SubsequentEventsTextBlock_A0DD90C0CAFF638570E93F8292784E19" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Subsequent Events [Text Block] </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_SubsequentEventsTextBlock" xlink:label="loc_us-gaap_SubsequentEventsTextBlock_A0DD90C0CAFF638570E93F8292784E19" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_SubsequentEventsTextBlock_A0DD90C0CAFF638570E93F8292784E19" xlink:to="lab_us-gaap_SubsequentEventsTextBlock_A0DD90C0CAFF638570E93F8292784E19" xlink:type="arc"/>
<link:label id="lab_us-gaap_ScheduleOfGoodwillTable_F636FB5A189A4F730CD3B4D08DAC4F85_terseLabel_en-US" xlink:label="lab_us-gaap_ScheduleOfGoodwillTable_F636FB5A189A4F730CD3B4D08DAC4F85" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Schedule of Goodwill [Table] </link:label>
<link:label id="lab_us-gaap_ScheduleOfGoodwillTable_F636FB5A189A4F730CD3B4D08DAC4F85_label_en-US" xlink:label="lab_us-gaap_ScheduleOfGoodwillTable_F636FB5A189A4F730CD3B4D08DAC4F85" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Schedule of Goodwill [Table] </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ScheduleOfGoodwillTable" xlink:label="loc_us-gaap_ScheduleOfGoodwillTable_F636FB5A189A4F730CD3B4D08DAC4F85" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ScheduleOfGoodwillTable_F636FB5A189A4F730CD3B4D08DAC4F85" xlink:to="lab_us-gaap_ScheduleOfGoodwillTable_F636FB5A189A4F730CD3B4D08DAC4F85" xlink:type="arc"/>
<link:label id="lab_us-gaap_StatementBusinessSegmentsAxis_522C215A3A0C5A2BA6FCB4D08DAD6EB3_terseLabel_en-US" xlink:label="lab_us-gaap_StatementBusinessSegmentsAxis_522C215A3A0C5A2BA6FCB4D08DAD6EB3" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Business Segments [Axis] </link:label>
<link:label id="lab_us-gaap_StatementBusinessSegmentsAxis_522C215A3A0C5A2BA6FCB4D08DAD6EB3_label_en-US" xlink:label="lab_us-gaap_StatementBusinessSegmentsAxis_522C215A3A0C5A2BA6FCB4D08DAD6EB3" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Segments [Axis] </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_StatementBusinessSegmentsAxis" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_522C215A3A0C5A2BA6FCB4D08DAD6EB3" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_522C215A3A0C5A2BA6FCB4D08DAD6EB3" xlink:to="lab_us-gaap_StatementBusinessSegmentsAxis_522C215A3A0C5A2BA6FCB4D08DAD6EB3" xlink:type="arc"/>
<link:label id="lab_us-gaap_SegmentDomain_F58ADC95980EF447D578B4D08DAD55D7_terseLabel_en-US" xlink:label="lab_us-gaap_SegmentDomain_F58ADC95980EF447D578B4D08DAD55D7" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Segment [Domain] </link:label>
<link:label id="lab_us-gaap_SegmentDomain_F58ADC95980EF447D578B4D08DAD55D7_label_en-US" xlink:label="lab_us-gaap_SegmentDomain_F58ADC95980EF447D578B4D08DAD55D7" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Segments [Domain] </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_SegmentDomain" xlink:label="loc_us-gaap_SegmentDomain_F58ADC95980EF447D578B4D08DAD55D7" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_SegmentDomain_F58ADC95980EF447D578B4D08DAD55D7" xlink:to="lab_us-gaap_SegmentDomain_F58ADC95980EF447D578B4D08DAD55D7" xlink:type="arc"/>
<link:label id="lab_it_ResearchSegmentMember_6A3F58061B54E339A6EAB4D08DAD1A5A_terseLabel_en-US" xlink:label="lab_it_ResearchSegmentMember_6A3F58061B54E339A6EAB4D08DAD1A5A" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Research </link:label>
<link:label id="lab_it_ResearchSegmentMember_6A3F58061B54E339A6EAB4D08DAD1A5A_label_en-US" xlink:label="lab_it_ResearchSegmentMember_6A3F58061B54E339A6EAB4D08DAD1A5A" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Research Segment [Member] </link:label>
<link:label id="lab_it_ResearchSegmentMember_6A3F58061B54E339A6EAB4D08DAD1A5A_documentation_en-US" xlink:label="lab_it_ResearchSegmentMember_6A3F58061B54E339A6EAB4D08DAD1A5A" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US"> -- None. No documentation exists for this element. -- </link:label>
<link:loc xlink:href="it-20161231.xsd#it_ResearchSegmentMember" xlink:label="loc_it_ResearchSegmentMember_6A3F58061B54E339A6EAB4D08DAD1A5A" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_it_ResearchSegmentMember_6A3F58061B54E339A6EAB4D08DAD1A5A" xlink:to="lab_it_ResearchSegmentMember_6A3F58061B54E339A6EAB4D08DAD1A5A" xlink:type="arc"/>
<link:label id="lab_it_ConsultingMember_A6A61481D80422C94A6AB4D08DAD3BE6_terseLabel_en-US" xlink:label="lab_it_ConsultingMember_A6A61481D80422C94A6AB4D08DAD3BE6" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Consulting </link:label>
<link:label id="lab_it_ConsultingMember_A6A61481D80422C94A6AB4D08DAD3BE6_label_en-US" xlink:label="lab_it_ConsultingMember_A6A61481D80422C94A6AB4D08DAD3BE6" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Consulting [Member] </link:label>
<link:label id="lab_it_ConsultingMember_A6A61481D80422C94A6AB4D08DAD3BE6_documentation_en-US" xlink:label="lab_it_ConsultingMember_A6A61481D80422C94A6AB4D08DAD3BE6" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US"> -- None. No documentation exists for this element. -- </link:label>
<link:loc xlink:href="it-20161231.xsd#it_ConsultingMember" xlink:label="loc_it_ConsultingMember_A6A61481D80422C94A6AB4D08DAD3BE6" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_it_ConsultingMember_A6A61481D80422C94A6AB4D08DAD3BE6" xlink:to="lab_it_ConsultingMember_A6A61481D80422C94A6AB4D08DAD3BE6" xlink:type="arc"/>
<link:label id="lab_it_EventsMember_44C2E8919B88E8231189B4D08DADECB1_terseLabel_en-US" xlink:label="lab_it_EventsMember_44C2E8919B88E8231189B4D08DADECB1" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Events </link:label>
<link:label id="lab_it_EventsMember_44C2E8919B88E8231189B4D08DADECB1_label_en-US" xlink:label="lab_it_EventsMember_44C2E8919B88E8231189B4D08DADECB1" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Events [Member] </link:label>
<link:label id="lab_it_EventsMember_44C2E8919B88E8231189B4D08DADECB1_documentation_en-US" xlink:label="lab_it_EventsMember_44C2E8919B88E8231189B4D08DADECB1" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US"> -- None. No documentation exists for this element. -- </link:label>
<link:loc xlink:href="it-20161231.xsd#it_EventsMember" xlink:label="loc_it_EventsMember_44C2E8919B88E8231189B4D08DADECB1" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_it_EventsMember_44C2E8919B88E8231189B4D08DADECB1" xlink:to="lab_it_EventsMember_44C2E8919B88E8231189B4D08DADECB1" xlink:type="arc"/>
<link:label id="lab_us-gaap_GoodwillLineItems_37AB4E861D1D2D721CBEB4D08DAD4AF5_terseLabel_en-US" xlink:label="lab_us-gaap_GoodwillLineItems_37AB4E861D1D2D721CBEB4D08DAD4AF5" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Goodwill [Line Items] </link:label>
<link:label id="lab_us-gaap_GoodwillLineItems_37AB4E861D1D2D721CBEB4D08DAD4AF5_label_en-US" xlink:label="lab_us-gaap_GoodwillLineItems_37AB4E861D1D2D721CBEB4D08DAD4AF5" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Goodwill [Line Items] </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_GoodwillLineItems" xlink:label="loc_us-gaap_GoodwillLineItems_37AB4E861D1D2D721CBEB4D08DAD4AF5" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_GoodwillLineItems_37AB4E861D1D2D721CBEB4D08DAD4AF5" xlink:to="lab_us-gaap_GoodwillLineItems_37AB4E861D1D2D721CBEB4D08DAD4AF5" xlink:type="arc"/>
<link:label id="lab_us-gaap_GoodwillRollForward_E5A06B99A94187CDDF65B4D08DB27AFD_terseLabel_en-US" xlink:label="lab_us-gaap_GoodwillRollForward_E5A06B99A94187CDDF65B4D08DB27AFD" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Goodwill [Roll Forward] </link:label>
<link:label id="lab_us-gaap_GoodwillRollForward_E5A06B99A94187CDDF65B4D08DB27AFD_label_en-US" xlink:label="lab_us-gaap_GoodwillRollForward_E5A06B99A94187CDDF65B4D08DB27AFD" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Goodwill [Roll Forward] </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_GoodwillRollForward" xlink:label="loc_us-gaap_GoodwillRollForward_E5A06B99A94187CDDF65B4D08DB27AFD" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_GoodwillRollForward_E5A06B99A94187CDDF65B4D08DB27AFD" xlink:to="lab_us-gaap_GoodwillRollForward_E5A06B99A94187CDDF65B4D08DB27AFD" xlink:type="arc"/>
<link:label id="lab_us-gaap_Goodwill_CB5B5FD9308ABFB453FAB4D08DB2D76E_periodStartLabel_en-US" xlink:label="lab_us-gaap_Goodwill_CB5B5FD9308ABFB453FAB4D08DB2D76E" xlink:role="http://www.xbrl.org/2003/role/periodStartLabel" xlink:type="resource" xml:lang="en-US"> Beginning Balance </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_Goodwill" xlink:label="loc_us-gaap_Goodwill_CB5B5FD9308ABFB453FAB4D08DB2D76E" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_Goodwill_CB5B5FD9308ABFB453FAB4D08DB2D76E" xlink:to="lab_us-gaap_Goodwill_CB5B5FD9308ABFB453FAB4D08DB2D76E" xlink:type="arc"/>
<link:label id="lab_us-gaap_GoodwillAcquiredDuringPeriod_A5907368CEC0111F1857B4D08DB2FCA3_verboseLabel_en-US" xlink:label="lab_us-gaap_GoodwillAcquiredDuringPeriod_A5907368CEC0111F1857B4D08DB2FCA3" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:type="resource" xml:lang="en-US"> Additions due to acquisition </link:label>
<link:label id="lab_us-gaap_GoodwillAcquiredDuringPeriod_A5907368CEC0111F1857B4D08DB2FCA3_label_en-US" xlink:label="lab_us-gaap_GoodwillAcquiredDuringPeriod_A5907368CEC0111F1857B4D08DB2FCA3" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Goodwill, Acquired During Period </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_GoodwillAcquiredDuringPeriod" xlink:label="loc_us-gaap_GoodwillAcquiredDuringPeriod_A5907368CEC0111F1857B4D08DB2FCA3" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_GoodwillAcquiredDuringPeriod_A5907368CEC0111F1857B4D08DB2FCA3" xlink:to="lab_us-gaap_GoodwillAcquiredDuringPeriod_A5907368CEC0111F1857B4D08DB2FCA3" xlink:type="arc"/>
<link:label id="lab_us-gaap_GoodwillTranslationAndPurchaseAccountingAdjustments_B712001E23BABD7695EDB4D08DB2658B_terseLabel_en-US" xlink:label="lab_us-gaap_GoodwillTranslationAndPurchaseAccountingAdjustments_B712001E23BABD7695EDB4D08DB2658B" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Foreign currency translation adjustments </link:label>
<link:label id="lab_us-gaap_GoodwillTranslationAndPurchaseAccountingAdjustments_B712001E23BABD7695EDB4D08DB2658B_label_en-US" xlink:label="lab_us-gaap_GoodwillTranslationAndPurchaseAccountingAdjustments_B712001E23BABD7695EDB4D08DB2658B" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Goodwill, Translation and Purchase Accounting Adjustments </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_GoodwillTranslationAndPurchaseAccountingAdjustments" xlink:label="loc_us-gaap_GoodwillTranslationAndPurchaseAccountingAdjustments_B712001E23BABD7695EDB4D08DB2658B" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_GoodwillTranslationAndPurchaseAccountingAdjustments_B712001E23BABD7695EDB4D08DB2658B" xlink:to="lab_us-gaap_GoodwillTranslationAndPurchaseAccountingAdjustments_B712001E23BABD7695EDB4D08DB2658B" xlink:type="arc"/>
<link:label id="lab_us-gaap_Goodwill_644D539A241234416BB3B4D08DB21738_periodEndLabel_en-US" xlink:label="lab_us-gaap_Goodwill_644D539A241234416BB3B4D08DB21738" xlink:role="http://www.xbrl.org/2003/role/periodEndLabel" xlink:type="resource" xml:lang="en-US"> Ending Balance </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_Goodwill" xlink:label="loc_us-gaap_Goodwill_644D539A241234416BB3B4D08DB21738" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_Goodwill_644D539A241234416BB3B4D08DB21738" xlink:to="lab_us-gaap_Goodwill_644D539A241234416BB3B4D08DB21738" xlink:type="arc"/>
<link:label id="lab_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_E5ADE6276E9CFB29910F53EF8B65896A_terseLabel_en-US" xlink:label="lab_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_E5ADE6276E9CFB29910F53EF8B65896A" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Schedule of Business Acquisitions, by Acquisition [Table] </link:label>
<link:label id="lab_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_E5ADE6276E9CFB29910F53EF8B65896A_label_en-US" xlink:label="lab_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_E5ADE6276E9CFB29910F53EF8B65896A" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Schedule of Business Acquisitions, by Acquisition [Table] </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable" xlink:label="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_E5ADE6276E9CFB29910F53EF8B65896A" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_E5ADE6276E9CFB29910F53EF8B65896A" xlink:to="lab_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_E5ADE6276E9CFB29910F53EF8B65896A" xlink:type="arc"/>
<link:label id="lab_us-gaap_StatementScenarioAxis_C81C452F516E6BA00EF553EF8B65383C_terseLabel_en-US" xlink:label="lab_us-gaap_StatementScenarioAxis_C81C452F516E6BA00EF553EF8B65383C" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Scenario [Axis] </link:label>
<link:label id="lab_us-gaap_StatementScenarioAxis_C81C452F516E6BA00EF553EF8B65383C_label_en-US" xlink:label="lab_us-gaap_StatementScenarioAxis_C81C452F516E6BA00EF553EF8B65383C" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Scenario [Axis] </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_StatementScenarioAxis" xlink:label="loc_us-gaap_StatementScenarioAxis_C81C452F516E6BA00EF553EF8B65383C" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_StatementScenarioAxis_C81C452F516E6BA00EF553EF8B65383C" xlink:to="lab_us-gaap_StatementScenarioAxis_C81C452F516E6BA00EF553EF8B65383C" xlink:type="arc"/>
<link:label id="lab_us-gaap_ScenarioUnspecifiedDomain_836DB82A237B843CC74E53EF8B65E49A_terseLabel_en-US" xlink:label="lab_us-gaap_ScenarioUnspecifiedDomain_836DB82A237B843CC74E53EF8B65E49A" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Scenario, Unspecified [Domain] </link:label>
<link:label id="lab_us-gaap_ScenarioUnspecifiedDomain_836DB82A237B843CC74E53EF8B65E49A_label_en-US" xlink:label="lab_us-gaap_ScenarioUnspecifiedDomain_836DB82A237B843CC74E53EF8B65E49A" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Scenario, Unspecified [Domain] </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ScenarioUnspecifiedDomain" xlink:label="loc_us-gaap_ScenarioUnspecifiedDomain_836DB82A237B843CC74E53EF8B65E49A" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ScenarioUnspecifiedDomain_836DB82A237B843CC74E53EF8B65E49A" xlink:to="lab_us-gaap_ScenarioUnspecifiedDomain_836DB82A237B843CC74E53EF8B65E49A" xlink:type="arc"/>
<link:label id="lab_us-gaap_ScenarioForecastMember_2A0210D3430159CAE9AF53EF8B654D0E_terseLabel_en-US" xlink:label="lab_us-gaap_ScenarioForecastMember_2A0210D3430159CAE9AF53EF8B654D0E" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Scenario, Forecast </link:label>
<link:label id="lab_us-gaap_ScenarioForecastMember_2A0210D3430159CAE9AF53EF8B654D0E_label_en-US" xlink:label="lab_us-gaap_ScenarioForecastMember_2A0210D3430159CAE9AF53EF8B654D0E" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Scenario, Forecast [Member] </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ScenarioForecastMember" xlink:label="loc_us-gaap_ScenarioForecastMember_2A0210D3430159CAE9AF53EF8B654D0E" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ScenarioForecastMember_2A0210D3430159CAE9AF53EF8B654D0E" xlink:to="lab_us-gaap_ScenarioForecastMember_2A0210D3430159CAE9AF53EF8B654D0E" xlink:type="arc"/>
<link:label id="lab_it_AcquisitionandIntegrationChargesMember_192B1905B6AB6CBF808053EF8B66C80E_terseLabel_en-US" xlink:label="lab_it_AcquisitionandIntegrationChargesMember_192B1905B6AB6CBF808053EF8B66C80E" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Acquisition and Integration Charges </link:label>
<link:label id="lab_it_AcquisitionandIntegrationChargesMember_192B1905B6AB6CBF808053EF8B66C80E_label_en-US" xlink:label="lab_it_AcquisitionandIntegrationChargesMember_192B1905B6AB6CBF808053EF8B66C80E" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Acquisition and Integration Charges [Member] </link:label>
<link:label id="lab_it_AcquisitionandIntegrationChargesMember_192B1905B6AB6CBF808053EF8B66C80E_documentation_en-US" xlink:label="lab_it_AcquisitionandIntegrationChargesMember_192B1905B6AB6CBF808053EF8B66C80E" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US"> Acquisition and Integration Charges [Member] </link:label>
<link:loc xlink:href="it-20161231.xsd#it_AcquisitionandIntegrationChargesMember" xlink:label="loc_it_AcquisitionandIntegrationChargesMember_192B1905B6AB6CBF808053EF8B66C80E" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_it_AcquisitionandIntegrationChargesMember_192B1905B6AB6CBF808053EF8B66C80E" xlink:to="lab_it_AcquisitionandIntegrationChargesMember_192B1905B6AB6CBF808053EF8B66C80E" xlink:type="arc"/>
<link:label id="lab_us-gaap_ContingentConsiderationByTypeAxis_8727FBBC04FA60E6B0DC53EF8B6638C8_terseLabel_en-US" xlink:label="lab_us-gaap_ContingentConsiderationByTypeAxis_8727FBBC04FA60E6B0DC53EF8B6638C8" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Contingent Consideration by Type [Axis] </link:label>
<link:label id="lab_us-gaap_ContingentConsiderationByTypeAxis_8727FBBC04FA60E6B0DC53EF8B6638C8_label_en-US" xlink:label="lab_us-gaap_ContingentConsiderationByTypeAxis_8727FBBC04FA60E6B0DC53EF8B6638C8" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Contingent Consideration by Type [Axis] </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ContingentConsiderationByTypeAxis" xlink:label="loc_us-gaap_ContingentConsiderationByTypeAxis_8727FBBC04FA60E6B0DC53EF8B6638C8" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ContingentConsiderationByTypeAxis_8727FBBC04FA60E6B0DC53EF8B6638C8" xlink:to="lab_us-gaap_ContingentConsiderationByTypeAxis_8727FBBC04FA60E6B0DC53EF8B6638C8" xlink:type="arc"/>
<link:label id="lab_us-gaap_ContingentConsiderationTypeDomain_E8E01A122C4A9A2AAE0753EF8B660D8C_terseLabel_en-US" xlink:label="lab_us-gaap_ContingentConsiderationTypeDomain_E8E01A122C4A9A2AAE0753EF8B660D8C" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Contingent Consideration Type [Domain] </link:label>
<link:label id="lab_us-gaap_ContingentConsiderationTypeDomain_E8E01A122C4A9A2AAE0753EF8B660D8C_label_en-US" xlink:label="lab_us-gaap_ContingentConsiderationTypeDomain_E8E01A122C4A9A2AAE0753EF8B660D8C" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Contingent Consideration Type [Domain] </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ContingentConsiderationTypeDomain" xlink:label="loc_us-gaap_ContingentConsiderationTypeDomain_E8E01A122C4A9A2AAE0753EF8B660D8C" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_ContingentConsiderationTypeDomain_E8E01A122C4A9A2AAE0753EF8B660D8C" xlink:to="lab_us-gaap_ContingentConsiderationTypeDomain_E8E01A122C4A9A2AAE0753EF8B660D8C" xlink:type="arc"/>
<link:label id="lab_it_ContingentConsiderationEarnoutMember_BCC6014A38D7D368717253EF8B667DD5_terseLabel_en-US" xlink:label="lab_it_ContingentConsiderationEarnoutMember_BCC6014A38D7D368717253EF8B667DD5" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Contingent consideration, earn-out </link:label>
<link:label id="lab_it_ContingentConsiderationEarnoutMember_BCC6014A38D7D368717253EF8B667DD5_label_en-US" xlink:label="lab_it_ContingentConsiderationEarnoutMember_BCC6014A38D7D368717253EF8B667DD5" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Contingent Consideration, Earn-out [Member] </link:label>
<link:label id="lab_it_ContingentConsiderationEarnoutMember_BCC6014A38D7D368717253EF8B667DD5_documentation_en-US" xlink:label="lab_it_ContingentConsiderationEarnoutMember_BCC6014A38D7D368717253EF8B667DD5" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US"> Contingent Consideration, Earn-out </link:label>
<link:loc xlink:href="it-20161231.xsd#it_ContingentConsiderationEarnoutMember" xlink:label="loc_it_ContingentConsiderationEarnoutMember_BCC6014A38D7D368717253EF8B667DD5" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_it_ContingentConsiderationEarnoutMember_BCC6014A38D7D368717253EF8B667DD5" xlink:to="lab_it_ContingentConsiderationEarnoutMember_BCC6014A38D7D368717253EF8B667DD5" xlink:type="arc"/>
<link:label id="lab_it_ContingentConsiderationEmployeeConditionsMember_50711B6CC4EA3F94ECC453EF8B660218_terseLabel_en-US" xlink:label="lab_it_ContingentConsiderationEmployeeConditionsMember_50711B6CC4EA3F94ECC453EF8B660218" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Contingent consideration, employee conditions </link:label>
<link:label id="lab_it_ContingentConsiderationEmployeeConditionsMember_50711B6CC4EA3F94ECC453EF8B660218_label_en-US" xlink:label="lab_it_ContingentConsiderationEmployeeConditionsMember_50711B6CC4EA3F94ECC453EF8B660218" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Contingent Consideration, Employee Conditions [Member] </link:label>
<link:label id="lab_it_ContingentConsiderationEmployeeConditionsMember_50711B6CC4EA3F94ECC453EF8B660218_documentation_en-US" xlink:label="lab_it_ContingentConsiderationEmployeeConditionsMember_50711B6CC4EA3F94ECC453EF8B660218" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US"> Contingent Consideration, Employee Conditions [Member] </link:label>
<link:loc xlink:href="it-20161231.xsd#it_ContingentConsiderationEmployeeConditionsMember" xlink:label="loc_it_ContingentConsiderationEmployeeConditionsMember_50711B6CC4EA3F94ECC453EF8B660218" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_it_ContingentConsiderationEmployeeConditionsMember_50711B6CC4EA3F94ECC453EF8B660218" xlink:to="lab_it_ContingentConsiderationEmployeeConditionsMember_50711B6CC4EA3F94ECC453EF8B660218" xlink:type="arc"/>
<link:label id="lab_it_MarketVisioOyMember_F7DCE5F72FF1909097A253EF8B67EBEC_terseLabel_en-US" xlink:label="lab_it_MarketVisioOyMember_F7DCE5F72FF1909097A253EF8B67EBEC" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Market-Visio Oy </link:label>
<link:label id="lab_it_MarketVisioOyMember_F7DCE5F72FF1909097A253EF8B67EBEC_label_en-US" xlink:label="lab_it_MarketVisioOyMember_F7DCE5F72FF1909097A253EF8B67EBEC" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Market-Visio Oy [Member] </link:label>
<link:label id="lab_it_MarketVisioOyMember_F7DCE5F72FF1909097A253EF8B67EBEC_documentation_en-US" xlink:label="lab_it_MarketVisioOyMember_F7DCE5F72FF1909097A253EF8B67EBEC" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US"> Market-Visio Oy [Member] </link:label>
<link:loc xlink:href="it-20161231.xsd#it_MarketVisioOyMember" xlink:label="loc_it_MarketVisioOyMember_F7DCE5F72FF1909097A253EF8B67EBEC" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_it_MarketVisioOyMember_F7DCE5F72FF1909097A253EF8B67EBEC" xlink:to="lab_it_MarketVisioOyMember_F7DCE5F72FF1909097A253EF8B67EBEC" xlink:type="arc"/>
<link:label id="lab_it_SircleITInc.Member_9355F78F6D80B7D516D253EF8B678A83_terseLabel_en-US" xlink:label="lab_it_SircleITInc.Member_9355F78F6D80B7D516D253EF8B678A83" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> SircleIT Inc. </link:label>
<link:label id="lab_it_SircleITInc.Member_9355F78F6D80B7D516D253EF8B678A83_label_en-US" xlink:label="lab_it_SircleITInc.Member_9355F78F6D80B7D516D253EF8B678A83" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> SircleIT Inc. [Member] </link:label>
<link:label id="lab_it_SircleITInc.Member_9355F78F6D80B7D516D253EF8B678A83_documentation_en-US" xlink:label="lab_it_SircleITInc.Member_9355F78F6D80B7D516D253EF8B678A83" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US"> SircleIT Inc. [Member] </link:label>
<link:loc xlink:href="it-20161231.xsd#it_SircleITInc.Member" xlink:label="loc_it_SircleITInc.Member_9355F78F6D80B7D516D253EF8B678A83" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_it_SircleITInc.Member_9355F78F6D80B7D516D253EF8B678A83" xlink:to="lab_it_SircleITInc.Member_9355F78F6D80B7D516D253EF8B678A83" xlink:type="arc"/>
<link:label id="lab_it_MachinaResearchMember_04BC3DC03AD7C64F15F553EF8B678325_terseLabel_en-US" xlink:label="lab_it_MachinaResearchMember_04BC3DC03AD7C64F15F553EF8B678325" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Machina Research </link:label>
<link:label id="lab_it_MachinaResearchMember_04BC3DC03AD7C64F15F553EF8B678325_label_en-US" xlink:label="lab_it_MachinaResearchMember_04BC3DC03AD7C64F15F553EF8B678325" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Machina Research [Member] </link:label>
<link:label id="lab_it_MachinaResearchMember_04BC3DC03AD7C64F15F553EF8B678325_documentation_en-US" xlink:label="lab_it_MachinaResearchMember_04BC3DC03AD7C64F15F553EF8B678325" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US"> Machina Research </link:label>
<link:loc xlink:href="it-20161231.xsd#it_MachinaResearchMember" xlink:label="loc_it_MachinaResearchMember_04BC3DC03AD7C64F15F553EF8B678325" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_it_MachinaResearchMember_04BC3DC03AD7C64F15F553EF8B678325" xlink:to="lab_it_MachinaResearchMember_04BC3DC03AD7C64F15F553EF8B678325" xlink:type="arc"/>
<link:label id="lab_it_SCMWorldMember_FD0C7240F20A6A47003753EF8B67A3D2_terseLabel_en-US" xlink:label="lab_it_SCMWorldMember_FD0C7240F20A6A47003753EF8B67A3D2" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> SCM World </link:label>
<link:label id="lab_it_SCMWorldMember_FD0C7240F20A6A47003753EF8B67A3D2_label_en-US" xlink:label="lab_it_SCMWorldMember_FD0C7240F20A6A47003753EF8B67A3D2" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> SCM World [Member] </link:label>
<link:label id="lab_it_SCMWorldMember_FD0C7240F20A6A47003753EF8B67A3D2_documentation_en-US" xlink:label="lab_it_SCMWorldMember_FD0C7240F20A6A47003753EF8B67A3D2" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US"> SCM World [Member] </link:label>
<link:loc xlink:href="it-20161231.xsd#it_SCMWorldMember" xlink:label="loc_it_SCMWorldMember_FD0C7240F20A6A47003753EF8B67A3D2" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_it_SCMWorldMember_FD0C7240F20A6A47003753EF8B67A3D2" xlink:to="lab_it_SCMWorldMember_FD0C7240F20A6A47003753EF8B67A3D2" xlink:type="arc"/>
<link:label id="lab_it_NuberaeBusinessS.L.andCapterraInc.Member_159CA23D979A579F903553EF8B679251_terseLabel_en-US" xlink:label="lab_it_NuberaeBusinessS.L.andCapterraInc.Member_159CA23D979A579F903553EF8B679251" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Nubera and Capterra </link:label>
<link:label id="lab_it_NuberaeBusinessS.L.andCapterraInc.Member_159CA23D979A579F903553EF8B679251_label_en-US" xlink:label="lab_it_NuberaeBusinessS.L.andCapterraInc.Member_159CA23D979A579F903553EF8B679251" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Nubera eBusiness S.L. and Capterra, Inc. [Member] </link:label>
<link:label id="lab_it_NuberaeBusinessS.L.andCapterraInc.Member_159CA23D979A579F903553EF8B679251_documentation_en-US" xlink:label="lab_it_NuberaeBusinessS.L.andCapterraInc.Member_159CA23D979A579F903553EF8B679251" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US"> Nubera eBusiness S.L. and Capterra, Inc. [Member] </link:label>
<link:loc xlink:href="it-20161231.xsd#it_NuberaeBusinessS.L.andCapterraInc.Member" xlink:label="loc_it_NuberaeBusinessS.L.andCapterraInc.Member_159CA23D979A579F903553EF8B679251" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_it_NuberaeBusinessS.L.andCapterraInc.Member_159CA23D979A579F903553EF8B679251" xlink:to="lab_it_NuberaeBusinessS.L.andCapterraInc.Member_159CA23D979A579F903553EF8B679251" xlink:type="arc"/>
<link:label id="lab_it_CapterraInc.Member_0E52ABD77003D67C83A353EF8B67977A_terseLabel_en-US" xlink:label="lab_it_CapterraInc.Member_0E52ABD77003D67C83A353EF8B67977A" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Capterra </link:label>
<link:label id="lab_it_CapterraInc.Member_0E52ABD77003D67C83A353EF8B67977A_label_en-US" xlink:label="lab_it_CapterraInc.Member_0E52ABD77003D67C83A353EF8B67977A" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Capterra, Inc. [Member] </link:label>
<link:label id="lab_it_CapterraInc.Member_0E52ABD77003D67C83A353EF8B67977A_documentation_en-US" xlink:label="lab_it_CapterraInc.Member_0E52ABD77003D67C83A353EF8B67977A" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US"> Capterra, Inc. [Member] </link:label>
<link:loc xlink:href="it-20161231.xsd#it_CapterraInc.Member" xlink:label="loc_it_CapterraInc.Member_0E52ABD77003D67C83A353EF8B67977A" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_it_CapterraInc.Member_0E52ABD77003D67C83A353EF8B67977A" xlink:to="lab_it_CapterraInc.Member_0E52ABD77003D67C83A353EF8B67977A" xlink:type="arc"/>
<link:label id="lab_it_SoftwareAdviceInc.Member_71AD770AC7B3F3826E5F53EF8B6782B0_terseLabel_en-US" xlink:label="lab_it_SoftwareAdviceInc.Member_71AD770AC7B3F3826E5F53EF8B6782B0" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Software Advice </link:label>
<link:label id="lab_it_SoftwareAdviceInc.Member_71AD770AC7B3F3826E5F53EF8B6782B0_label_en-US" xlink:label="lab_it_SoftwareAdviceInc.Member_71AD770AC7B3F3826E5F53EF8B6782B0" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Software Advice, Inc. [Member] </link:label>
<link:label id="lab_it_SoftwareAdviceInc.Member_71AD770AC7B3F3826E5F53EF8B6782B0_documentation_en-US" xlink:label="lab_it_SoftwareAdviceInc.Member_71AD770AC7B3F3826E5F53EF8B6782B0" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US"> Software Advice, Inc. [Member] </link:label>
<link:loc xlink:href="it-20161231.xsd#it_SoftwareAdviceInc.Member" xlink:label="loc_it_SoftwareAdviceInc.Member_71AD770AC7B3F3826E5F53EF8B6782B0" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_it_SoftwareAdviceInc.Member_71AD770AC7B3F3826E5F53EF8B6782B0" xlink:to="lab_it_SoftwareAdviceInc.Member_71AD770AC7B3F3826E5F53EF8B6782B0" xlink:type="arc"/>
<link:label id="lab_us-gaap_BusinessAcquisitionLineItems_6E6527C0BADF3892D7D953EF8B673EC7_terseLabel_en-US" xlink:label="lab_us-gaap_BusinessAcquisitionLineItems_6E6527C0BADF3892D7D953EF8B673EC7" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Business Acquisition [Line Items] </link:label>
<link:label id="lab_us-gaap_BusinessAcquisitionLineItems_6E6527C0BADF3892D7D953EF8B673EC7_label_en-US" xlink:label="lab_us-gaap_BusinessAcquisitionLineItems_6E6527C0BADF3892D7D953EF8B673EC7" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Business Acquisition [Line Items] </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_BusinessAcquisitionLineItems" xlink:label="loc_us-gaap_BusinessAcquisitionLineItems_6E6527C0BADF3892D7D953EF8B673EC7" xlink:type="locator"/>
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<link:label id="lab_us-gaap_BusinessAcquisitionPercentageOfVotingInterestsAcquired_AE32C4C9F19717BC62C753EF8B67B959_terseLabel_en-US" xlink:label="lab_us-gaap_BusinessAcquisitionPercentageOfVotingInterestsAcquired_AE32C4C9F19717BC62C753EF8B67B959" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Percentage of voting interests acquired </link:label>
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<link:label id="lab_us-gaap_PaymentsToAcquireBusinessesGross_B70640DD87FB8000D52953EF8B68D083_terseLabel_en-US" xlink:label="lab_us-gaap_PaymentsToAcquireBusinessesGross_B70640DD87FB8000D52953EF8B68D083" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Aggregate purchase price </link:label>
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<link:label id="lab_us-gaap_PaymentsToAcquireBusinessesNetOfCashAcquired_5195516068BB9745350153EF8B68C751_verboseLabel_en-US" xlink:label="lab_us-gaap_PaymentsToAcquireBusinessesNetOfCashAcquired_5195516068BB9745350153EF8B68C751" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:type="resource" xml:lang="en-US"> Net cash paid for acquisition </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_PaymentsToAcquireBusinessesNetOfCashAcquired" xlink:label="loc_us-gaap_PaymentsToAcquireBusinessesNetOfCashAcquired_5195516068BB9745350153EF8B68C751" xlink:type="locator"/>
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<link:label id="lab_us-gaap_OtherPaymentsToAcquireBusinesses_4EEB6FCE3DB600B604E453EF8B681247_terseLabel_en-US" xlink:label="lab_us-gaap_OtherPaymentsToAcquireBusinesses_4EEB6FCE3DB600B604E453EF8B681247" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Acquisition cash place in escrow </link:label>
<link:label id="lab_us-gaap_OtherPaymentsToAcquireBusinesses_4EEB6FCE3DB600B604E453EF8B681247_label_en-US" xlink:label="lab_us-gaap_OtherPaymentsToAcquireBusinesses_4EEB6FCE3DB600B604E453EF8B681247" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Other Payments to Acquire Businesses </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_OtherPaymentsToAcquireBusinesses" xlink:label="loc_us-gaap_OtherPaymentsToAcquireBusinesses_4EEB6FCE3DB600B604E453EF8B681247" xlink:type="locator"/>
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<link:label id="lab_us-gaap_BusinessCombinationContingentConsiderationArrangementsRangeOfOutcomesValueHigh_21BEEFFC1CF2C537790553EF8B687FAB_terseLabel_en-US" xlink:label="lab_us-gaap_BusinessCombinationContingentConsiderationArrangementsRangeOfOutcomesValueHigh_21BEEFFC1CF2C537790553EF8B687FAB" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Contingent consideration arrangements, maximum value (up to) </link:label>
<link:label id="lab_us-gaap_BusinessCombinationContingentConsiderationArrangementsRangeOfOutcomesValueHigh_21BEEFFC1CF2C537790553EF8B687FAB_label_en-US" xlink:label="lab_us-gaap_BusinessCombinationContingentConsiderationArrangementsRangeOfOutcomesValueHigh_21BEEFFC1CF2C537790553EF8B687FAB" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Business Combination, Contingent Consideration Arrangements, Range of Outcomes, Value, High </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_BusinessCombinationContingentConsiderationArrangementsRangeOfOutcomesValueHigh" xlink:label="loc_us-gaap_BusinessCombinationContingentConsiderationArrangementsRangeOfOutcomesValueHigh_21BEEFFC1CF2C537790553EF8B687FAB" xlink:type="locator"/>
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<link:label id="lab_it_BusinessCombinationContingentConsiderationArrangementsRangeofOutcomesMaximumValuePeriodOfExpenseRecognition_246840D1C4368B9EBF8653EF8B68D2B5_terseLabel_en-US" xlink:label="lab_it_BusinessCombinationContingentConsiderationArrangementsRangeofOutcomesMaximumValuePeriodOfExpenseRecognition_246840D1C4368B9EBF8653EF8B68D2B5" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Contingent consideration arrangements, maximum value, period of expense recognition </link:label>
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<link:label id="lab_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibles_C17F11FEF63F9CF4F6DE53EF8B6823BD_terseLabel_en-US" xlink:label="lab_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibles_C17F11FEF63F9CF4F6DE53EF8B6823BD" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Business combination, amortizable intangible assets recognized </link:label>
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<link:label id="lab_it_OtherPaymentstoAcquireBusinessesRestrictedCash_E7294F7ABA04101F6FC453EF8B68F289_terseLabel_en-US" xlink:label="lab_it_OtherPaymentstoAcquireBusinessesRestrictedCash_E7294F7ABA04101F6FC453EF8B68F289" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Other payments to acquire businesses, restricted cash </link:label>
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<link:label id="lab_it_OtherPaymentstoAcquireBusinessesRestrictedCash_E7294F7ABA04101F6FC453EF8B68F289_documentation_en-US" xlink:label="lab_it_OtherPaymentstoAcquireBusinessesRestrictedCash_E7294F7ABA04101F6FC453EF8B68F289" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US"> Other Payments to Acquire Businesses, Restricted Cash </link:label>
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<link:label id="lab_us-gaap_GoodwillPurchaseAccountingAdjustments_EBCAF954E2A4C5E3CDAA53EF8B6887A4_terseLabel_en-US" xlink:label="lab_us-gaap_GoodwillPurchaseAccountingAdjustments_EBCAF954E2A4C5E3CDAA53EF8B6887A4" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Goodwill, purchase accounting adjustments </link:label>
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<link:label id="lab_us-gaap_AdditionalPaidInCapitalMember_9488D92729D51728315E3E94370F5D0F_terseLabel_en-US" xlink:label="lab_us-gaap_AdditionalPaidInCapitalMember_9488D92729D51728315E3E94370F5D0F" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Additional Paid-In Capital </link:label>
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<link:label id="lab_us-gaap_StockIssuedDuringPeriodValueShareBasedCompensationGross_2DC02F8904E97CCBECAF3E94370F2B48_terseLabel_en-US" xlink:label="lab_us-gaap_StockIssuedDuringPeriodValueShareBasedCompensationGross_2DC02F8904E97CCBECAF3E94370F2B48" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Issuances under stock plans </link:label>
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<link:label id="lab_us-gaap_StockAppreciationRightsSARSMember_A2B004A54A62B0C12763E53BFBE96525_verboseLabel_en-US" xlink:label="lab_us-gaap_StockAppreciationRightsSARSMember_A2B004A54A62B0C12763E53BFBE96525" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:type="resource" xml:lang="en-US"> Stock appreciation rights </link:label>
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<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_StockAppreciationRightsSARSMember_A2B004A54A62B0C12763E53BFBE96525" xlink:to="lab_us-gaap_StockAppreciationRightsSARSMember_A2B004A54A62B0C12763E53BFBE96525" xlink:type="arc"/>
<link:label id="lab_it_CommonStockEquivalentsCSEsMember_74BFD78692AB4594AF86E53BFBE95D2D_verboseLabel_en-US" xlink:label="lab_it_CommonStockEquivalentsCSEsMember_74BFD78692AB4594AF86E53BFBE95D2D" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:type="resource" xml:lang="en-US"> Common stock equivalents </link:label>
<link:label id="lab_it_CommonStockEquivalentsCSEsMember_74BFD78692AB4594AF86E53BFBE95D2D_label_en-US" xlink:label="lab_it_CommonStockEquivalentsCSEsMember_74BFD78692AB4594AF86E53BFBE95D2D" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Common Stock Equivalents CS Es [Member] </link:label>
<link:label id="lab_it_CommonStockEquivalentsCSEsMember_74BFD78692AB4594AF86E53BFBE95D2D_documentation_en-US" xlink:label="lab_it_CommonStockEquivalentsCSEsMember_74BFD78692AB4594AF86E53BFBE95D2D" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US"> Common stock equivalents (CSEs) </link:label>
<link:loc xlink:href="it-20161231.xsd#it_CommonStockEquivalentsCSEsMember" xlink:label="loc_it_CommonStockEquivalentsCSEsMember_74BFD78692AB4594AF86E53BFBE95D2D" xlink:type="locator"/>
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<link:label id="lab_us-gaap_RestrictedStockUnitsRSUMember_13F1BC617059F014756FE53BFBE9E2E1_verboseLabel_en-US" xlink:label="lab_us-gaap_RestrictedStockUnitsRSUMember_13F1BC617059F014756FE53BFBE9E2E1" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:type="resource" xml:lang="en-US"> Restricted stock units </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_RestrictedStockUnitsRSUMember" xlink:label="loc_us-gaap_RestrictedStockUnitsRSUMember_13F1BC617059F014756FE53BFBE9E2E1" xlink:type="locator"/>
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<link:label id="lab_us-gaap_AllocatedShareBasedCompensationExpense_30F2EC11B9659A33D0C4E53BFBE98D21_verboseLabel_en-US" xlink:label="lab_us-gaap_AllocatedShareBasedCompensationExpense_30F2EC11B9659A33D0C4E53BFBE98D21" xlink:role="http://www.xbrl.org/2003/role/verboseLabel" xlink:type="resource" xml:lang="en-US"> Stock-based compensation expense </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_AllocatedShareBasedCompensationExpense" xlink:label="loc_us-gaap_AllocatedShareBasedCompensationExpense_30F2EC11B9659A33D0C4E53BFBE98D21" xlink:type="locator"/>
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<link:label id="lab_us-gaap_Revenues_1D329C1B03BEF61F84FAE53BFB6A5974_terseLabel_en-US" xlink:label="lab_us-gaap_Revenues_1D329C1B03BEF61F84FAE53BFB6A5974" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Revenues </link:label>
<link:label id="lab_us-gaap_Revenues_1D329C1B03BEF61F84FAE53BFB6A5974_label_en-US" xlink:label="lab_us-gaap_Revenues_1D329C1B03BEF61F84FAE53BFB6A5974" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Revenues </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_Revenues" xlink:label="loc_us-gaap_Revenues_1D329C1B03BEF61F84FAE53BFB6A5974" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_Revenues_1D329C1B03BEF61F84FAE53BFB6A5974" xlink:to="lab_us-gaap_Revenues_1D329C1B03BEF61F84FAE53BFB6A5974" xlink:type="arc"/>
<link:label id="lab_us-gaap_OperatingExpenses_A695BFCAD7C3FF063977E53BFB6A20F6_negatedTerseLabel_en-US" xlink:label="lab_us-gaap_OperatingExpenses_A695BFCAD7C3FF063977E53BFB6A20F6" xlink:role="http://www.xbrl.org/2009/role/negatedTerseLabel" xlink:type="resource" xml:lang="en-US"> Corporate and other expenses </link:label>
<link:label id="lab_us-gaap_OperatingExpenses_A695BFCAD7C3FF063977E53BFB6A20F6_label_en-US" xlink:label="lab_us-gaap_OperatingExpenses_A695BFCAD7C3FF063977E53BFB6A20F6" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Operating Expenses </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_OperatingExpenses" xlink:label="loc_us-gaap_OperatingExpenses_A695BFCAD7C3FF063977E53BFB6A20F6" xlink:type="locator"/>
<link:labelArc order="1" xlink:arcrole="http://www.xbrl.org/2003/arcrole/concept-label" xlink:from="loc_us-gaap_OperatingExpenses_A695BFCAD7C3FF063977E53BFB6A20F6" xlink:to="lab_us-gaap_OperatingExpenses_A695BFCAD7C3FF063977E53BFB6A20F6" xlink:type="arc"/>
<link:label id="lab_us-gaap_IncomeStatementAbstract_920AC58F4A846EA0EFFCE53BFDA45D47_label_en-US" xlink:label="lab_us-gaap_IncomeStatementAbstract_920AC58F4A846EA0EFFCE53BFDA45D47" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Income Statement [Abstract] </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_IncomeStatementAbstract" xlink:label="loc_us-gaap_IncomeStatementAbstract_920AC58F4A846EA0EFFCE53BFDA45D47" xlink:type="locator"/>
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<link:label id="lab_us-gaap_RevenuesAbstract_5F7413CE5DDED58BC9B2E53BFDA4FF6F_terseLabel_en-US" xlink:label="lab_us-gaap_RevenuesAbstract_5F7413CE5DDED58BC9B2E53BFDA4FF6F" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Revenues: </link:label>
<link:label id="lab_us-gaap_RevenuesAbstract_5F7413CE5DDED58BC9B2E53BFDA4FF6F_label_en-US" xlink:label="lab_us-gaap_RevenuesAbstract_5F7413CE5DDED58BC9B2E53BFDA4FF6F" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Revenues [Abstract] </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_RevenuesAbstract" xlink:label="loc_us-gaap_RevenuesAbstract_5F7413CE5DDED58BC9B2E53BFDA4FF6F" xlink:type="locator"/>
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<link:label id="lab_us-gaap_SubscriptionRevenue_0B1284D517C99FEA4E90E53BFDA49870_terseLabel_en-US" xlink:label="lab_us-gaap_SubscriptionRevenue_0B1284D517C99FEA4E90E53BFDA49870" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Research </link:label>
<link:label id="lab_us-gaap_SubscriptionRevenue_0B1284D517C99FEA4E90E53BFDA49870_label_en-US" xlink:label="lab_us-gaap_SubscriptionRevenue_0B1284D517C99FEA4E90E53BFDA49870" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Subscription and Circulation Revenue </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_SubscriptionRevenue" xlink:label="loc_us-gaap_SubscriptionRevenue_0B1284D517C99FEA4E90E53BFDA49870" xlink:type="locator"/>
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<link:label id="lab_us-gaap_ContractsRevenue_D571F4E3FC38A75E91D7E53BFDA4FE9F_terseLabel_en-US" xlink:label="lab_us-gaap_ContractsRevenue_D571F4E3FC38A75E91D7E53BFDA4FE9F" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Consulting </link:label>
<link:label id="lab_us-gaap_ContractsRevenue_D571F4E3FC38A75E91D7E53BFDA4FE9F_label_en-US" xlink:label="lab_us-gaap_ContractsRevenue_D571F4E3FC38A75E91D7E53BFDA4FE9F" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Contracts Revenue </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_ContractsRevenue" xlink:label="loc_us-gaap_ContractsRevenue_D571F4E3FC38A75E91D7E53BFDA4FE9F" xlink:type="locator"/>
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<link:label id="lab_us-gaap_AdmissionsRevenue_A45F8BF015E4934C438AE53BFDA4D53D_terseLabel_en-US" xlink:label="lab_us-gaap_AdmissionsRevenue_A45F8BF015E4934C438AE53BFDA4D53D" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Events </link:label>
<link:label id="lab_us-gaap_AdmissionsRevenue_A45F8BF015E4934C438AE53BFDA4D53D_label_en-US" xlink:label="lab_us-gaap_AdmissionsRevenue_A45F8BF015E4934C438AE53BFDA4D53D" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Admissions Revenue </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_AdmissionsRevenue" xlink:label="loc_us-gaap_AdmissionsRevenue_A45F8BF015E4934C438AE53BFDA4D53D" xlink:type="locator"/>
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<link:label id="lab_us-gaap_SalesRevenueNet_C04FF9D5CDBEE037AE24E53BFDA48F56_totalLabel_en-US" xlink:label="lab_us-gaap_SalesRevenueNet_C04FF9D5CDBEE037AE24E53BFDA48F56" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:type="resource" xml:lang="en-US"> Total revenues </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_SalesRevenueNet" xlink:label="loc_us-gaap_SalesRevenueNet_C04FF9D5CDBEE037AE24E53BFDA48F56" xlink:type="locator"/>
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<link:label id="lab_us-gaap_CostsAndExpensesAbstract_B2CA741963D18E503C2EE53BFDA4CE2B_terseLabel_en-US" xlink:label="lab_us-gaap_CostsAndExpensesAbstract_B2CA741963D18E503C2EE53BFDA4CE2B" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Costs and expenses: </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_CostsAndExpensesAbstract" xlink:label="loc_us-gaap_CostsAndExpensesAbstract_B2CA741963D18E503C2EE53BFDA4CE2B" xlink:type="locator"/>
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<link:label id="lab_us-gaap_Depreciation_FF92611E1A3CAB8D5E0DE53BFDA59668_terseLabel_en-US" xlink:label="lab_us-gaap_Depreciation_FF92611E1A3CAB8D5E0DE53BFDA59668" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Depreciation </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_Depreciation" xlink:label="loc_us-gaap_Depreciation_FF92611E1A3CAB8D5E0DE53BFDA59668" xlink:type="locator"/>
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<link:label id="lab_us-gaap_CostsAndExpenses_28FBF259E8B3A61FFEC4E53BFDA5C5EB_totalLabel_en-US" xlink:label="lab_us-gaap_CostsAndExpenses_28FBF259E8B3A61FFEC4E53BFDA5C5EB" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:type="resource" xml:lang="en-US"> Total costs and expenses </link:label>
<link:label id="lab_us-gaap_CostsAndExpenses_28FBF259E8B3A61FFEC4E53BFDA5C5EB_label_en-US" xlink:label="lab_us-gaap_CostsAndExpenses_28FBF259E8B3A61FFEC4E53BFDA5C5EB" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Costs and Expenses </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_CostsAndExpenses" xlink:label="loc_us-gaap_CostsAndExpenses_28FBF259E8B3A61FFEC4E53BFDA5C5EB" xlink:type="locator"/>
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<link:label id="lab_us-gaap_OperatingIncomeLoss_9AEBB8396336D5F7FB51E53BFDA51EFA_terseLabel_en-US" xlink:label="lab_us-gaap_OperatingIncomeLoss_9AEBB8396336D5F7FB51E53BFDA51EFA" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Operating income </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_OperatingIncomeLoss" xlink:label="loc_us-gaap_OperatingIncomeLoss_9AEBB8396336D5F7FB51E53BFDA51EFA" xlink:type="locator"/>
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<link:label id="lab_us-gaap_InterestIncomeOperating_8720524A80BC20BFE2F5E53BFDA55E1D_terseLabel_en-US" xlink:label="lab_us-gaap_InterestIncomeOperating_8720524A80BC20BFE2F5E53BFDA55E1D" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Interest income </link:label>
<link:label id="lab_us-gaap_InterestIncomeOperating_8720524A80BC20BFE2F5E53BFDA55E1D_label_en-US" xlink:label="lab_us-gaap_InterestIncomeOperating_8720524A80BC20BFE2F5E53BFDA55E1D" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Interest Income, Operating </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_InterestIncomeOperating" xlink:label="loc_us-gaap_InterestIncomeOperating_8720524A80BC20BFE2F5E53BFDA55E1D" xlink:type="locator"/>
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<link:label id="lab_us-gaap_InterestExpense_EFF7FF4C79D18F85330BE53BFDA50BB2_negatedTerseLabel_en-US" xlink:label="lab_us-gaap_InterestExpense_EFF7FF4C79D18F85330BE53BFDA50BB2" xlink:role="http://www.xbrl.org/2009/role/negatedTerseLabel" xlink:type="resource" xml:lang="en-US"> Interest expense </link:label>
<link:label id="lab_us-gaap_InterestExpense_EFF7FF4C79D18F85330BE53BFDA50BB2_label_en-US" xlink:label="lab_us-gaap_InterestExpense_EFF7FF4C79D18F85330BE53BFDA50BB2" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Interest Expense </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_InterestExpense" xlink:label="loc_us-gaap_InterestExpense_EFF7FF4C79D18F85330BE53BFDA50BB2" xlink:type="locator"/>
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<link:label id="lab_us-gaap_OtherNonoperatingIncomeExpense_FF5A744CB1570563BC99E53BFDA5854E_terseLabel_en-US" xlink:label="lab_us-gaap_OtherNonoperatingIncomeExpense_FF5A744CB1570563BC99E53BFDA5854E" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Other income (expense), net </link:label>
<link:label id="lab_us-gaap_OtherNonoperatingIncomeExpense_FF5A744CB1570563BC99E53BFDA5854E_label_en-US" xlink:label="lab_us-gaap_OtherNonoperatingIncomeExpense_FF5A744CB1570563BC99E53BFDA5854E" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Other Nonoperating Income (Expense) </link:label>
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<link:label id="lab_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments_5C773378CAA3FD1F9FC8E53BFDA53AB6_totalLabel_en-US" xlink:label="lab_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments_5C773378CAA3FD1F9FC8E53BFDA53AB6" xlink:role="http://www.xbrl.org/2003/role/totalLabel" xlink:type="resource" xml:lang="en-US"> Income before income taxes </link:label>
<link:label id="lab_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments_5C773378CAA3FD1F9FC8E53BFDA53AB6_label_en-US" xlink:label="lab_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments_5C773378CAA3FD1F9FC8E53BFDA53AB6" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest </link:label>
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<link:label id="lab_us-gaap_EarningsPerShareAbstract_BF900BC465B2229B9763E53BFDA50A3E_terseLabel_en-US" xlink:label="lab_us-gaap_EarningsPerShareAbstract_BF900BC465B2229B9763E53BFDA50A3E" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Net income per share: </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_EarningsPerShareAbstract" xlink:label="loc_us-gaap_EarningsPerShareAbstract_BF900BC465B2229B9763E53BFDA50A3E" xlink:type="locator"/>
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<link:label id="lab_us-gaap_WeightedAverageNumberOfSharesOutstandingDilutedDisclosureItemsAbstract_C0BCBDB4CC5511E6C241E53BFDA613AB_terseLabel_en-US" xlink:label="lab_us-gaap_WeightedAverageNumberOfSharesOutstandingDilutedDisclosureItemsAbstract_C0BCBDB4CC5511E6C241E53BFDA613AB" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Weighted average shares outstanding: </link:label>
<link:label id="lab_us-gaap_WeightedAverageNumberOfSharesOutstandingDilutedDisclosureItemsAbstract_C0BCBDB4CC5511E6C241E53BFDA613AB_label_en-US" xlink:label="lab_us-gaap_WeightedAverageNumberOfSharesOutstandingDilutedDisclosureItemsAbstract_C0BCBDB4CC5511E6C241E53BFDA613AB" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Weighted Average Number of Shares Outstanding Reconciliation [Abstract] </link:label>
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<link:label id="lab_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_5D4528A766C4DAE1F25CE53BFDA6C821_terseLabel_en-US" xlink:label="lab_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_5D4528A766C4DAE1F25CE53BFDA6C821" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Basic (in shares) </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_WeightedAverageNumberOfSharesOutstandingBasic" xlink:label="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_5D4528A766C4DAE1F25CE53BFDA6C821" xlink:type="locator"/>
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<link:label id="lab_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_AA31887D831200252C25E53BFDA6BD05_terseLabel_en-US" xlink:label="lab_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_AA31887D831200252C25E53BFDA6BD05" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Diluted (in shares) </link:label>
<link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2016/elts/us-gaap-2016-01-31.xsd#us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding" xlink:label="loc_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_AA31887D831200252C25E53BFDA6BD05" xlink:type="locator"/>
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<link:label id="lab_it_DocumentAndEntityInformationAbstract_F32DB297D657D70606509913C27C2DA7_label_en-US" xlink:label="lab_it_DocumentAndEntityInformationAbstract_F32DB297D657D70606509913C27C2DA7" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Document and Entity Information [Abstract] </link:label>
<link:label id="lab_it_DocumentAndEntityInformationAbstract_F32DB297D657D70606509913C27C2DA7_documentation_en-US" xlink:label="lab_it_DocumentAndEntityInformationAbstract_F32DB297D657D70606509913C27C2DA7" xlink:role="http://www.xbrl.org/2003/role/documentation" xlink:type="resource" xml:lang="en-US"> -- None. No documentation exists for this element. -- </link:label>
<link:loc xlink:href="it-20161231.xsd#it_DocumentAndEntityInformationAbstract" xlink:label="loc_it_DocumentAndEntityInformationAbstract_F32DB297D657D70606509913C27C2DA7" xlink:type="locator"/>
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<link:label id="lab_dei_EntityRegistrantName_B0C2DC559D2D5DEDB1F19913C27E497C_terseLabel_en-US" xlink:label="lab_dei_EntityRegistrantName_B0C2DC559D2D5DEDB1F19913C27E497C" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Entity Registrant Name </link:label>
<link:label id="lab_dei_EntityRegistrantName_B0C2DC559D2D5DEDB1F19913C27E497C_label_en-US" xlink:label="lab_dei_EntityRegistrantName_B0C2DC559D2D5DEDB1F19913C27E497C" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Entity Registrant Name </link:label>
<link:loc xlink:href="http://xbrl.sec.gov/dei/2014/dei-2014-01-31.xsd#dei_EntityRegistrantName" xlink:label="loc_dei_EntityRegistrantName_B0C2DC559D2D5DEDB1F19913C27E497C" xlink:type="locator"/>
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<link:label id="lab_dei_EntityCentralIndexKey_36FD3F4E5D9A86F7A0F29913C27FF2C2_terseLabel_en-US" xlink:label="lab_dei_EntityCentralIndexKey_36FD3F4E5D9A86F7A0F29913C27FF2C2" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Entity Central Index Key </link:label>
<link:label id="lab_dei_EntityCentralIndexKey_36FD3F4E5D9A86F7A0F29913C27FF2C2_label_en-US" xlink:label="lab_dei_EntityCentralIndexKey_36FD3F4E5D9A86F7A0F29913C27FF2C2" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Entity Central Index Key </link:label>
<link:loc xlink:href="http://xbrl.sec.gov/dei/2014/dei-2014-01-31.xsd#dei_EntityCentralIndexKey" xlink:label="loc_dei_EntityCentralIndexKey_36FD3F4E5D9A86F7A0F29913C27FF2C2" xlink:type="locator"/>
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<link:label id="lab_dei_CurrentFiscalYearEndDate_86A5C07E0B2E13ADFA2F9913C27FC25A_terseLabel_en-US" xlink:label="lab_dei_CurrentFiscalYearEndDate_86A5C07E0B2E13ADFA2F9913C27FC25A" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Current Fiscal Year End Date </link:label>
<link:label id="lab_dei_CurrentFiscalYearEndDate_86A5C07E0B2E13ADFA2F9913C27FC25A_label_en-US" xlink:label="lab_dei_CurrentFiscalYearEndDate_86A5C07E0B2E13ADFA2F9913C27FC25A" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Current Fiscal Year End Date </link:label>
<link:loc xlink:href="http://xbrl.sec.gov/dei/2014/dei-2014-01-31.xsd#dei_CurrentFiscalYearEndDate" xlink:label="loc_dei_CurrentFiscalYearEndDate_86A5C07E0B2E13ADFA2F9913C27FC25A" xlink:type="locator"/>
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<link:label id="lab_dei_EntityFilerCategory_DD2F2A1F92C1671674629913C27F2715_terseLabel_en-US" xlink:label="lab_dei_EntityFilerCategory_DD2F2A1F92C1671674629913C27F2715" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Entity Filer Category </link:label>
<link:label id="lab_dei_EntityFilerCategory_DD2F2A1F92C1671674629913C27F2715_label_en-US" xlink:label="lab_dei_EntityFilerCategory_DD2F2A1F92C1671674629913C27F2715" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Entity Filer Category </link:label>
<link:loc xlink:href="http://xbrl.sec.gov/dei/2014/dei-2014-01-31.xsd#dei_EntityFilerCategory" xlink:label="loc_dei_EntityFilerCategory_DD2F2A1F92C1671674629913C27F2715" xlink:type="locator"/>
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<link:label id="lab_dei_DocumentType_AFC49FC408A7FE3DE8059913C28439E4_terseLabel_en-US" xlink:label="lab_dei_DocumentType_AFC49FC408A7FE3DE8059913C28439E4" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Document Type </link:label>
<link:label id="lab_dei_DocumentType_AFC49FC408A7FE3DE8059913C28439E4_label_en-US" xlink:label="lab_dei_DocumentType_AFC49FC408A7FE3DE8059913C28439E4" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Document Type </link:label>
<link:loc xlink:href="http://xbrl.sec.gov/dei/2014/dei-2014-01-31.xsd#dei_DocumentType" xlink:label="loc_dei_DocumentType_AFC49FC408A7FE3DE8059913C28439E4" xlink:type="locator"/>
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<link:label id="lab_dei_DocumentPeriodEndDate_15116421113EF4C8D5449913C2848450_terseLabel_en-US" xlink:label="lab_dei_DocumentPeriodEndDate_15116421113EF4C8D5449913C2848450" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Document Period End Date </link:label>
<link:label id="lab_dei_DocumentPeriodEndDate_15116421113EF4C8D5449913C2848450_label_en-US" xlink:label="lab_dei_DocumentPeriodEndDate_15116421113EF4C8D5449913C2848450" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Document Period End Date </link:label>
<link:loc xlink:href="http://xbrl.sec.gov/dei/2014/dei-2014-01-31.xsd#dei_DocumentPeriodEndDate" xlink:label="loc_dei_DocumentPeriodEndDate_15116421113EF4C8D5449913C2848450" xlink:type="locator"/>
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<link:label id="lab_dei_DocumentFiscalYearFocus_6061FC7ADA3BA6A200149913C284E0CF_terseLabel_en-US" xlink:label="lab_dei_DocumentFiscalYearFocus_6061FC7ADA3BA6A200149913C284E0CF" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Document Fiscal Year Focus </link:label>
<link:label id="lab_dei_DocumentFiscalYearFocus_6061FC7ADA3BA6A200149913C284E0CF_label_en-US" xlink:label="lab_dei_DocumentFiscalYearFocus_6061FC7ADA3BA6A200149913C284E0CF" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Document Fiscal Year Focus </link:label>
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<link:label id="lab_dei_DocumentFiscalPeriodFocus_4A2B90C370E96EDBC1329913C2844B0D_terseLabel_en-US" xlink:label="lab_dei_DocumentFiscalPeriodFocus_4A2B90C370E96EDBC1329913C2844B0D" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Document Fiscal Period Focus </link:label>
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<link:label id="lab_dei_AmendmentFlag_ACE39A07B0DF3850D6F39913C2843D2D_terseLabel_en-US" xlink:label="lab_dei_AmendmentFlag_ACE39A07B0DF3850D6F39913C2843D2D" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Amendment Flag </link:label>
<link:label id="lab_dei_AmendmentFlag_ACE39A07B0DF3850D6F39913C2843D2D_label_en-US" xlink:label="lab_dei_AmendmentFlag_ACE39A07B0DF3850D6F39913C2843D2D" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Amendment Flag </link:label>
<link:loc xlink:href="http://xbrl.sec.gov/dei/2014/dei-2014-01-31.xsd#dei_AmendmentFlag" xlink:label="loc_dei_AmendmentFlag_ACE39A07B0DF3850D6F39913C2843D2D" xlink:type="locator"/>
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<link:label id="lab_dei_EntityCommonStockSharesOutstanding_79ECB9F8165F116225D79913C284596C_terseLabel_en-US" xlink:label="lab_dei_EntityCommonStockSharesOutstanding_79ECB9F8165F116225D79913C284596C" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> Entity Common Stock, Shares Outstanding </link:label>
<link:label id="lab_dei_EntityCommonStockSharesOutstanding_79ECB9F8165F116225D79913C284596C_label_en-US" xlink:label="lab_dei_EntityCommonStockSharesOutstanding_79ECB9F8165F116225D79913C284596C" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Entity Common Stock, Shares Outstanding </link:label>
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<link:label id="lab_dei_EntityCurrentReportingStatus_11696F224B60650EDB669913C2851F34_label_en-US" xlink:label="lab_dei_EntityCurrentReportingStatus_11696F224B60650EDB669913C2851F34" xlink:role="http://www.xbrl.org/2003/role/label" xlink:type="resource" xml:lang="en-US"> Entity Current Reporting Status </link:label>
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<link:label id="lab_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleTable_7007DF57C6FDAFADCCA74797E157D6F1_terseLabel_en-US" xlink:label="lab_us-gaap_NewAccountingPronouncementsOrChangeInAccountingPrincipleTable_7007DF57C6FDAFADCCA74797E157D6F1" xlink:role="http://www.xbrl.org/2003/role/terseLabel" xlink:type="resource" xml:lang="en-US"> New Accounting Pronouncements or Change in Accounting Principle [Table] </link:label>
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