(a) In computing any period of time prescribed or allowed by these rules, by direction of the Board, or by any applicable statute which does not provide otherwise, the day from which the designated period of time begins to run shall not be included. The last day of the period so computed shall be included, unless it is a Saturday, Sunday, or legal holiday, in which event the period runs until the end of the next day which is not a Saturday, Sunday, or legal holiday.

(b) Whenever a paper is served on the Board or on any party by mail, paragraph (a) of this section will be deemed complied with if the envelope containing the paper is postmarked by the U.S. Postal Service within the time period allowed, computed as in paragraph (a) of this section. If there is no such postmark, or it is not legible, other evidence, such as, but not limited to, certified mail receipts, certificate of service and affidavits, may be used to establish the mailing date.

(c) A waiver of the time limitations for filing a paper, other than a notice of appeal, may be requested by proper motion filed in accordance with §§ 802.217 and 802.219.