16.  Service of Papers Other Than Subpoenas

Papers shall be served personally or by mail, addressed to the party upon whom service is to be made. Copies of complaints, answers and briefs shall be filed directly with the Board. The party filing any other paper with the Board shall send a copy thereof to the opposing party, noting on the paper filed with the Board that a copy has been so furnished. Subpoenas shall be served as provided in Rule 21.