Within a reasonable time after the closing of the record and receipt of the transcript, all parties and participants may file, simultaneously unless otherwise directed by the Presiding Officer, post-hearing briefs, including proposed findings of fact and conclusions of law, as well as a proposed order. The Presiding Officer shall establish a date certain for the filing of the briefs, which shall not exceed fifty (50) days after the closing of the record except in unusual circumstances. The briefs shall be in writing and shall be served upon all parties. The briefs of all parties shall contain adequate references to the record and authorities relied upon. Replies shall be filed within fifteen (15) days of the date for the filing of briefs unless otherwise established by the Presiding Officer. The parties and participants may waive either or both submissions.