Business and Services Restructuring and Mainline 2012-2013 Tolls Application Abbreviations Page 1 of 8

ABBREVIATIONS Abbreviation Terminology ABC BC Border export delivery point AECO AECO Gas Storage Partnership AFUDC Allowance For Funds Used during Construction Alberta System Extension Extension of the TransCanada Alberta System service Alberta System Tariff NGTL’s Gas Transportation Tariff AOS Authorized Overrun Service Application Business and Services Restructuring and Mainline 2012-2013 Tolls Application ARP Alternate Receipt Point ATCO Pipelines ATCO Gas and Pipelines Ltd. ATWACC After Tax Weighted Average Cost of Capital AUC Alberta Utilities Commission BAPE Bureau d'audiences publiques sur l'environnement Basin Western Sedimentary Basin Base Year Toll year from January 1 to December 31, 2010 BC British Columbia Board National Energy Board BWMQ Brown, Williams, Moorhead, and Quinn, Inc. CAPP Canadian Association of Petroleum Producers CDA Central Delivery Area CDQ Contract Demand Quantity Centram SSDA Centra South Delivery Area Concentric Concentric Energy Advisors, Inc. CR Capacity release DDA Distributor Delivery Area Depreciation Study Mainline Depreciation Study Business and Services Restructuring and Mainline 2012-2013 Tolls Application Abbreviations Page 2 of 8

Abbreviation Terminology DOH Distance of Haul ECR Enhanced Capacity Release EDA Eastern Delivery Area EDB Towers Watson Energy Data Base EIA Energy Information Agency ESU Executive share units ET Eastern Triangle Extension Extension of the TransCanada Alberta System service EZT Eastern Zone Toll FERC Federal Energy Regulatory Commission Filing Manual National Energy Board Filing Manual, as revised FBT Firm Backhaul Transportation Service FDPS First Devoted to Public Service Foothills Foothills Pipe Lines Ltd. Forecast Year Toll year from January 1 to December 31, 2011 FST Firm Service Tendered FT Firm Transport FT-D NGTL firm transportation – delivery FT-DW Firm Winter Delivery Service FT-P NGTL firm transportation – points-to-point FT-R NGTL firm transportation – Receipt FT-SN Firm Transportation Short Notice FT-RN Firm Transportation – Receipt Non-renewable FTE Full-Time Equivalent GFI Gannett Fleming Inc. GBA Gas Balancing Agreement Business and Services Restructuring and Mainline 2012-2013 Tolls Application Abbreviations Page 3 of 8

Abbreviation Terminology GH-3-96 National Energy Board Reasons for Decision, TransCanada Pipelines Limited, GH-3-1996, Facilities GH-3-97 National Energy Board Reasons for Decision, Ltd. On behalf of Alliance Pipeline Limited Partnership, GH-3-1997, Facilities and Tolls & Tariffs GH-5-89 National Energy Board Reasons for Decision, TransCanada Pipelines Limited, GH-5-1989, Facilities and Tolling Matters GH-1-2006 National Energy Board Reasons for Decision GH-1-2006 GH-1-2011 National Energy Board, Kinder Morgan LNG Operations General Partnership Kitimat LNG Export License Application GH-4-88 National Energy Board Reasons for Decision, TransCanada, GH-4-1988, Facilities GH-5-2008 National Energy Board Reasons for Decision, TransCanada, GH-5-20088GH-5-2008, Jurisdiction and Facilities GLGT Great Lakes Gas Transmission Company GPIS Gas Plant In Service GPUAR Gas Pipeline Uniform Accounting Regulations GPUC Gas plant under construction GRR Gross Revenue Requirement GTL gas to liquids IC Incentive compensation Integration Integration of the commercial operations of the assets of ATCO Pipelines with those owned by NGTL IPA Integrated Public Awareness IRR Internal Rate of Return IS Information services ITB Interruptible Transportation Service - Backhaul IT Interruptible Service IT-D NGTL Interruptible Service - Delivery Business and Services Restructuring and Mainline 2012-2013 Tolls Application Abbreviations Page 4 of 8

Abbreviation Terminology IT-R Interruptible Service - Receipt JSD Junior Subordinated Debentures Keystone TransCanada GP Ltd. KM LNG Kitimat LNG LBAs Limited Balancing Agreements LDCs Local Distribution Companies LNG Liquified natural gas LRS Load Retention Services LT-WFS Long-Term Winter Firm Service LTD Long-term Disability LTIC Long term incentive compensation M&NP Maritimes and Northeast Pipeline Mainline TransCanada Mainline Mainline Final Tolls tolls for transportation services on the Mainline provided between January 1 2012 and December 31 2013 MFP Multi-Year Fixed-Price Service MH-1-2006 National Energy Board Reasons for Decision, TransCanada Pipelines Limited and TransCanada Keystone Pipeline GP Ltd., MH-1-2006, Transfer of Facilities MHPS Multiple Handshakes and Pooling Service NBJ North Bay Junction NEB National Energy Board NEB Act National Energy Board Act NGTL NOVA Gas Transmission Ltd. NIT NOVA Inventory Transfer NOL Northern Line NPV Net Present Value Business and Services Restructuring and Mainline 2012-2013 Tolls Application Abbreviations Page 5 of 8

Abbreviation Terminology October Supplement October 31, 2011 filing for 2012 and 2013 revenue requirement and proposed tolls OEB Ontario Energy Board OH-1-2009 National Energy Board Reasons for Decision OH-1-2009 OM&A Operations, Maintenance and Administrative OPEB Other Post Employment Benefits OT Overrun Transportation Service PALS Parking and Loans Service Prairies Prairies Line Proposal TransCanada Business Services Restructuring Proposal PSU Performance share units PUP Performance unit payments RAM Risk Alleviation Mechanism Régie Régie de l'énergie R&D Research and development Revised Interim 2011 Tolls Tolls approved by Order AO-1-TG1-04-2010 dated February 24, 2011, effective March 1, 2011 Restructuring Proposal TransCanada Business Services Restructuring Proposal REX Rockies Express RH-1-70 National Energy Board Reasons for Decision, In the Matter of TransCanada PipeLines Limited, RH-1-70 (Tolls Application – Phase I), December 1971 RH-1-72 National Energy Board Reasons for Decision, In the Matter of TransCanada PipeLines Limited Tolls Application – Phase I, issued 27 January 1972 RH-1-88 National Energy Board Reasons for Decision, In the Matter of TransCanada PipeLines Limited, RH-1-88 RH-1-97 National Energy Board Reasons for Decision, TransCanada Pipelines Limited, RH-1-97, Tolling Matters Business and Services Restructuring and Mainline 2012-2013 Tolls Application Abbreviations Page 6 of 8

Abbreviation Terminology RH-1-99 National Energy Board Reasons for Decision, TransCanada Pipelines Limited, RH-1-99, Tariff RH-1-2000 National Energy Board Reasons for Decision, Maritimes & Northeast Pipeline Management Ltd., RH-1-2000, Tolls RH-1-2001 National Energy Board Reasons for Decision, TransCanada Pipelines Limited, RH-1-2001,Tolls and Tariff RH-1-2002 National Energy Board Reasons for Decision, In the Matter of TransCanada PipeLines Limited, RH-1-2002, Tolls and Tariff RH-1-2005 National Energy Board Reasons for Decision in the Matter of Pipelines Inc., RH-1-2005, Tolls RH-1-2006 National Energy Board Reasons for Decision, In the Matter of TransCanada PipeLines Limited, RH-1-2006, Tolls and Services RH-1-2007 National Energy Board Reason for Decision, In the Matter of TransCanada PipeLines Limited, RH-1-2007, Receipt Point Application RH-1-2008 National Energy Board Reason for Decision, Trans Québec & Maritimes Inc., RH-1-2008, March 2009, Cost of Capital RH-2-91 National Energy Board Reasons for Decision In the Matter of Interprovincial Pipe Line Inc. Application dated 27 June 1991 for new tolls effective January 1 1992, RH-2-91, June 1992 RH-2-94 National Energy Board Reason for Decision: TransCanada PipeLines Limited, Westcoast Energy Inc., Foothills Pipe Lines Ltd., Alberta Natural Gas Company Ltd., Trans Québec & Maritimes Inc., Interprovincial Pipe Line Inc., Trans Mountain Pipe Line Company Ltd., Trans-Northern Pipeline Inc., RH-2-94 March 1995, Cost of Capital RH-2-95 National Energy Board Reasons for Decision, TransCanada Pipelines Limited, RH-2-95 RH-2-2001 National Energy Board Reasons for Decision, BC Gas Utility Ltd., RH-2-2001, Tolls RH-2-2004 National Energy Board Reasons for Decision, In the Matter of TransCanada PipeLines Limited, RH-2-2004 Phase II Business and Services Restructuring and Mainline 2012-2013 Tolls Application Abbreviations Page 7 of 8

Abbreviation Terminology RH-3-2004 National Energy Board Reasons for Decision, TransCanada Pipelines Limited, RH-2-2004, North Bay Junction Application RH-4-91 National Energy Board Reasons for Decision, In the Matter of TransCanada PipeLines Limited, RH-4-91 RH-4-93 National Energy Board Reasons for Decision, TransCanada Pipelines Limited, RH-4-93, Tolls RH-4-2001 National Energy Board Reasons for Decision, In the Matter of TransCanada PipeLines Limited, RH-4-2001, Cost of Capital, June 2002 RH-R-2-94 National Energy Board Reasons for Decision, Multi-Client, RH-R-2-94, RHW-1-2010 National Energy Board Reasons for Decision, in the Matter of NOVA Gas Transmission Ltd. new Toll Design Methodology, issued 12 August 2010 RHW-2-2005 National Energy Board Reasons for Decision, In the Matter of TransCanada PipeLines Limited Amendments to the Interruptible Toll Service to Reflect Modifications to FT- RAM Pilot R&O Repair and overhaul ROE Rate of Return on Equity SCC Stress corrosion cracking Settlement Mainline 2007-2011 Settlement Settlement Orders Mainline 2007-2011 Settlement was approved by Board Order TG-06-2007 and amended by TG-01-2008 and TG-06- 2009 SGS Small General Service SMB Saskatchewan/Manitoba Border Status Quo TransCanada Pipeline Systems existing tolling methodology STFT Short Term Firm Transportation Service STS Storage Transportation Service STS-L Storage Transportation Service-Linked Business and Services Restructuring and Mainline 2012-2013 Tolls Application Abbreviations Page 8 of 8

Abbreviation Terminology ST-SN Short Term Short Notice Service SWZT Southwest Zone Toll Test Year 2012 Toll year from January 1 to December 31, 2012 Test Year 2013 Toll year from January 1 to December 31, 2013 TBO Transportation by others TDC Total Direct Compensation Throughput Study TransCanada 2012-2013 Canadian Mainline Throughput Study (Appendix C1) TransCanada TransCanada PipeLines Limited TransCanada Contribution Voluntary contribution to reduce the Mainline revenue requirement for 2012 and 2013 TransCanada Pipeline Systems TransCanada’s Canadian federally regulated natural gas transmission businesses (Mainline, Alberta System and Foothills System) TTF Mainline Tolls and Tariff Task Force TTFP NGTL Tolls, Tariff, Facilities and Procedures Committee TQM Trans Québec & Maritimes Pipeline Inc. Union Union Gas Limited UDCs Unutilized Demand Charges US United States WCSB Western Canada Sedimentary Basin