(a) Filing. All documents submitted to the Secretary shall be filed with the Secretary of Labor, U.S. Department of Labor, 200 Constitution Ave., N.W., Washington, DC 20210.

(b) Number of copies. An original and four copies of all documents shall be filed.

(c) Computation of time for delivery by mail. Documents are not deemed filed with the Secretary until actually received by the Secretary either on or before the due date. No additional time shall be added where service of a document requiring action within a prescribed time was made by mail.

(d) Manner and proof of service. A copy of each document filed with the Secretary shall be served upon all other parties involved in the proceeding. Service under this section shall be by personal delivery or by mail. Service by mail is deemed effected at the time of mailing to the last known address.