Transmission means electric transmission, network or point-to-point service, ancillary services or other methods of electric transmission, or the interconnection with jurisdictional transmission facilities, under part 35 of this chapter; and natural gas transportation, storage, exchange, backhaul, or displacement service provided pursuant to subparts B or G of part 284 of this chapter.
18 CFR § 358.3
Affiliate of a specified entity means:
(1) Another person that controls, is controlled by or is under common control with, the specified entity. An affiliate includes a division of the specified entity that operates as a functional unit.
(2) For any exempt wholesale generator (as defined under § 366.1 of this chapter), affiliate shall have the meaning set forth in § 366.1 of this chapter, or any successor provision.
(3) “Control” as used in this definition means the direct or indirect authority, whether acting alone or in conjunction with others, to direct or cause to direct the management policies of an entity. A voting interest of 10 percent or more creates a rebuttable presumption of control.