(a) Every paper required to be served on opposing parties and filed in the Office in any priority, protest, or appeal proceeding, must be served by the Secretary in the manner provided in Sec. 97.403.
(b) The requirement in certain sections that a specified paper shall be served includes a requirement that all related supporting papers shall also be served. Proof of such service upon other parties to the proceeding must be made before the supporting papers will be considered by the Commissioner or Secretary.