(a) All time periods in this part that are stated in
terms of days are calendar days unless otherwise stated.
(b)
A document shall be deemed timely if it is received or postmarked
before the expiration of the applicable filing period, or, in the
absence of a legible postmark, if it is received by mail within five
days of the expiration of the applicable filing period.
(c)
The time limits in this part are subject to waiver, estoppel, and
equitable tolling.
(d) The first day counted shall be the day
after the event from which the time period begins to run and the last
day of the period shall be included, unless it falls on a Saturday,
Sunday, or federal holiday, in which case the period shall be extended
to include the next business day.