Each party who is an interested party shall submit to the Commission, no later than five (5) business days prior to the date of the hearing specified in the notice of scheduling, a prehearing brief. Prehearing briefs shall be signed and shall include a table of contents and shall be filed electronically, and nine (9) true paper copies shall be submitted on the same business day. The prehearing brief should present a party's case concisely and shall, to the extent possible, refer to the record and include information and arguments which the party believes relevant to the subject matter of the Commission's determination under section 705(b) or section 735(b) of the Act. Any person not an interested party may submit a brief written statement of information pertinent to the investigation within the time specified and the same manner specified for filing of prehearing briefs.