At the time a motion for summary determination under Sec. 210.18(a) or a motion for termination under Sec. 210.21(a) is made, or when it is found that a party is in default under Sec. 210.16, or at the close of the reception of evidence in any hearing held pursuant to this part (except as provided in Sec. 210.63), or within a reasonable time thereafter fixed by the administrative law judge, any party may file proposed findings of fact and conclusions of law, together with reasons therefor. When appropriate, briefs in support of the proposed findings of fact and conclusions of law may be filed with the administrative law judge for his consideration. Such proposals and briefs shall be in writing, shall be served upon all parties in accordance with Sec. 210.4(g), and shall contain adequate references to the record and the authorities on which the submitter is relying.