Any party served with such petition may, within 14 days after service thereof, respond to the petition, admitting or denying its allegations. Eight copies of such response shall be filed with the Board in Washington, DC. Such response shall be printed or otherwise legibly duplicated: Provided however, That carbon copies of typewritten materials will not be accepted. Such response shall immediately be served on all other parties to the proceeding, and a statement of service shall be filed in accordance with the provisions of Sec. 102.114(b) of these rules. [51 FR 23749, July 1, 1986]