18 C.F.R. § 385.209 : Conservation of Power and Water Resources — FEDERAL ENERGY REGULATORY COMMISSION, DEPARTMENT OF ENERGY — PROCEDURAL RULES — RULES OF PRACTICE AND PROCEDURE — PLEADINGS, TARIFF AND RATE FILINGS, NOTICES OF TARIFF OR RATE EXAMINATION, ORDERS TO SHOW CAUSE, INTERVENTION, AND SUMMARY DISPOSITION — Notices of tariff or rate examination and orders to show cause (Rule 209)

(a) Issuance.
(1) If the Commission seeks to determine the validity of any rate, rate schedule, tariff, tariff schedule, fare, charge, or term or condition of service, or any classification, contract, practice, or any related regulation established by and for the applicant which is demanded, observed, charged, or collected, the Commission will initiate a proceeding by issuing a notice of tariff or rate examination.
(2) The Commission may initiate a proceeding against a person by issuing an order to show cause.
(b) Contents. A notice of examination or an order to show cause will contain a statement of the matters about which the Commission is inquiring, and a statement of the authority under which the Commission is acting. The statement is tentative and sets forth issues to be considered by the Commission.
(c) Answers. A person who is ordered to show cause must answer in accordance with Rule 213.

18 C.F.R. §385.209