(a) Initial written statements of position and written testimony with supporting affidavits on the issues. These materials must be filed on the date set by the Commission or the presiding officer.

(b) Written responses, rebuttal testimony with supporting affidavits directed to the initial statements and testimony of other participants, and proposed written questions for the Presiding Officer to consider for submittal to persons sponsoring testimony submitted under paragraph (a) of this section. These materials shall be filed within 20 days of the filing of the materials submitted under paragraph (a) of this section, unless the Commission or Presiding Officer directs otherwise. Proposed written questions directed to rebuttal testimony for the Presiding Officer to consider for submittal to persons offering such testimony shall be filed within 7 days of the filing of the rebuttal testimony.

(c) Written concluding statements of position on the issues. These materials shall be filed within 20 days of the filing of the materials submitted under paragraph (b) of this section, unless the Commission or the Presiding Officer directs otherwise.