18 CFR §154.112

1. (a)The Commission may permit a special rate schedule to be filed in the form of an agreement in the case of a special operating arrangement, previously certificated pursuant to part 157 of this chapter, such as for the exchange of natural gas. The special rate schedule must contain a title page showing the parties to the agreement, the date of the agreement, a brief description of services to be rendered, and the designation: “Rate Schedule X-[number].” Special rate schedules may not contain any supplements. Modifications must be made by inserting revised sheets, sections or the entire document as appropriate. Special rate schedules must be included in a separate volume of the tariff. Each such separate volume must contain a table of contents which is incorporated as a sheet or section in the open access transmission tariff.
2. (b)Contracts for service pursuant to part 284 of this chapter that deviate in any material aspect from the form of service agreement must be filed. Such non-conforming agreements must be referenced in the open access transmission tariff.