(a) Within 10 days after the conclusion of the hearing, or, if no hearing is held, within 20 days after the filing of the petitioner's brief under Rule 906(b)(3) (pleadings), a participant may file with the Secretary of the Commission for the presiding officer, and serve upon the other participants proposed findings of fact and conclusions of law, comments in support thereof and any objections with respect to procedural rulings of the presiding officer.
(b) Within 10 days after the filing of proposed findings of fact and conclusions of law under paragraph (a) of this section, a participant may file, and must serve on other participants, a reply thereto.