The term party, whenever used in these Rules, shall include any natural person, corporation, association, firm, partnership, trustee, receiver, agency, public or private organization, or governmental agency. A party requesting official action subject to these Rules shall be designated as applicant. A party whose petition for leave to intervene is granted pursuant to § 201.78 shall be designated as intervenor. Only a party as designated in this section may introduce evidence or examine witnesses at hearings.

The Assistant General Counsel, Chief, Division of Operating Subsidy Contracts, shall be a party to all proceedings involving operating-differential subsidy contracts. The Assistant General Counsel and his representatives shall be designated as Public Counsel and shall be served with copies of all papers, pleadings, and documents in such proceedings. In addition the General Counsel may designate any member of his staff to serve as Staff Counsel in contract appeal cases or any other proceeding governed by the regulations in this part. Public Counsel or Staff Counsel shall participate in any proceeding to which he is a party, to the extent he deems required in the public interest, subject to the separation of functions required by section 5(c) of the Administrative Procedure Act.

Upon petition and for good cause shown, the Administration may order a substitution of parties; except that in case of death of a party substitution may be ordered upon suggestion and without the filing of a petition.