(a) Only a person served by the post office in which the Postal Service has issued a decision to close or consolidate a post office may file an appeal of the decision with the Commission.

(b) Any other person served by the same post office under review who desires to participate in the proceeding, or any Postmaster, counsel, agent, or other person authorized or recognized by the Postal Service as such person's representative, may participate in an appeal by submitting comments.

(c) Except for persons identified in paragraph (a) or (b) of this section, the designated Public Representative, and the Postal Service, no other person may participate in a proceeding to consider the appeal of a Postal Service determination to close or consolidate a post office.

(d) Opposition to a person asserting eligibility for participation shall be made within three days of that person's first filing in the proceeding.