Effective Date: from Wednesday, December 26, 2007 (close of business) to Tuesday, January 8, 2008 (close of business)

Futures Contracts: Demarcation Index Swap (DI), SoCal Index Swap (IF), Dominion Index Swap (IH), CenterPoint Index Swap (II), San Juan Index Swap (IJ), PG&E City Gate Index Swap (IK), El Paso/Permian Index Swap (IL), Henry Hub Index Swap (IN), Dawn Index Swap (IO), Houston Ship Channel Index Swap (IP), ANR OK Index Swap (IQ), Rockies Index Swap (IR), Chicago Index Swap (IS), Transco Zone 6 Index Swap (IT), Sumas Index Swap (IU), Panhandle Index Swap (IV), NGPL Mid-Continent Index Swap (IW), TETCO M-3 Index Swap (IX), Waha Index Swap (IY), NGPL Tex/OK Index Swap (OI) and Ventura Index Swap (VI).

Contract Months: All Months

Note: The revised margin Tiers are in bold.

* After January 8, 2008, Original Tiers apply.