E-11 Exhibit Designation Nature of Exhibit Previously Filed as Exhibit to: 4(a) Indenture (for unsecured debt securities), dated as of September 1, 1997, between OPCo and Bankers Trust Company (now The Bank of New York Mellon Trust Company, N.A. as assignee of Deutsche Bank Trust Company Americas), as Trustee. Registration Statement No. 333-49595, Ex 4(a)(b)(c) Registration Statement No. 333-106242, Ex 4( b )( c )( d ) Registration Statement No. 333-127913, Ex 4( ) Registration Statement No. 333-139802, Ex 4( b )( c )( d ) Registration Statement No. 333-161537, Ex 4( Registration Statement No. 333-211192, Ex 4(b) Registration Statement No. 333-230094, Ex 4(b) 4(a)(1) Resignation of Deutsche Bank Trust Company Americas, as Trustee and appointment of The Bank of New York Mellon Trust Company, N.A. as Trustee of Indenture with OPCo dated as of September 1, 1997. Form 8-K, Item 8.01 dated October 8, 2018 4(b) Indenture (for unsecured debt securities), dated as of February 1, 2003, between OPCo and Bank One, N.A., as Trustee. Registration Statement No. 333-127913, Ex 4( d )( e )( f ) 4(c) Indenture (for unsecured debt securities), dated as of September 1, 1997, between CSPCo (predecessor in interest to OPCo) and Bankers Trust Company, as Trustee. Registration Statement No. 333-54025, Ex 4(a)(b)(c)(d) Registration Statement No. 333-128174, Ex 4( b )( c )( d ) Registration Statement No. 333-150603, Ex 4(b) 4(d) Indenture (for unsecured debt securities), dated as of February 1, 2003, between CSPCo (predecessor in interest to OPCo) and Bank One, N.A., as Trustee. Registration Statement No. 333-128174, Ex 4( e )( f )( g ) Registration Statement No. 333-150603, Ex 4(b) 4(e) First Supplemental Indenture, dated as of December 31, 2011, by and between OPCo and The Bank of New York Mellon Trust Company, N.A., as trustee, supplementing the Indenture dated as of September 1, 1997 between CSPCo (predecessor in interest to OPCo) and the trustee. Form 8-K, Ex 4.1 dated January 6, 2012 4(f) Third  Supplemental  Indenture,  dated  as  of December 31, 2011, by and between OPCo and The Bank of New York Mellon Trust Company, N.A., as trustee, supplementing the Indenture dated as of February 14, 2003 between CSPCo (predecessor in interest to OPCo) and the trustee. Form 8-K, Ex 4.2 dated January 6, 2012 4(g) Company Order and Officers Certificate to The Bank of New York Mellon Trust Company, N.A. dated May 22, 2019 establishing the terms of the 4.00% Senior Notes Series O due 2049. Form 8-K, Ex 4(a) dated May 22, 2019