(a) The appeals official shall arrange such conferences with the concerned parties as are necessary, including (if requested by the appellant) an oral presentation.

(b) The appeals official may require either party to submit any additional documents, oral or written testimony, or other items of evidence which he considers necessary for a complete review of the agency decision.

(c) All documentary evidence submitted by one party to the appeal action shall be made available to the other party (or parties), except that availability of proprietary information may be restricted by the party holding the proprietary interest in such information.