The ISDA GTMA Annex is designed to document trades in the English physical electricity or power market. The GTMA Annex relates to the Grid Trade Master Agreement published by the Futures and Options Association and provides terms that apply to transactions involving the purchase or sale of power or options on power. It permits users to bring such trades under their ISDA Master Agreement architecture and to make certain elections with respect to the Grid Trade Master Agreement.

(Parties may also refer to Sub-Annex G of the 2005 ISDA Commodity Definitions)