Each party may submit to the Commission on or before a date specified in the notice of investigation issued pursuant to § 207.12 a written brief containing information and arguments pertinent to the subject matter of the investigation. Briefs shall be signed, shall include a table of contents, and shall contain no more than fifty (50) double spaced and single sided pages of textual material, on stationery measuring 81/2×11 inches. Any person not a party may submit a brief written statement of information pertinent to the investigation within the time specified for the filing of briefs. In addition, the presiding official may permit persons to file within a specified time answers to questions or requests made by the Commission's staff. If he deems it appropriate, the Director shall hold a conference. The conference, if any, shall be held in accordance with the procedures in § 201.13 of this chapter, except that in connection with its presentation a party may file witness testimony with the Secretary no later than three (3) days before the conference. The Director may request the appearance of witnesses, take testimony, and administer oaths.