39 CFR 3010.140: Opportunity to comment.

Except for proceedings involving an appeal of a Postal Service determination to close or consolidate a post office, any person may submit comments in public proceedings before the Commission. An opportunity to provide a reply to comments shall be at the discretion of the Commission, or the presiding officer if one is appointed. The scope and timing of comments and reply comments may be specified by notice, order, or presiding officer's ruling. There is no requirement to intervene in a proceeding as a party in order to submit comments.