All communications hereunder shall be in writing and, if sent to the Initial Purchasers, shall be mailed or delivered to Citigroup Global Markets Inc., 388 Greenwich Street, New York, New York 10013, Attention: General Counsel, Facsimile: (646) 291-1469; and if sent to the Partnership, shall be mailed or delivered to the Partnership at 1000 Louisiana Street, Suite 4300, Houston, Texas 77002, Attention: Chief Financial Officer; with a copy to Vinson & Elkins L.L.P., 1001 Fannin Street, Suite 2500, Houston, Texas 77002, Attention: Christopher S. Collins.