37 CFR §41.4

1. (a)Extensions of time. Extensions of time will be granted only on a showing of good cause except as otherwise provided by rule.
2. (b)Late filings.
   1. (1)A late filing that results in either an application becoming abandoned or a reexamination prosecution becoming terminated under § 1.550(d) or § 1.957(b) of this title or limited under § 1.957(c) of this title may be revived as set forth in § 1.137 of this title.
   2. (2)A late filing that does not result in either an application becoming abandoned or a reexamination prosecution becoming terminated under § 1.550(d) or § 1.957(b) of this title or limited under § 1.957(c) of this title will be excused upon a showing of excusable neglect or a Board determination that consideration on the merits would be in the interest of justice.
3. (c)Scope. This section governs all proceedings before the Board, but does not apply to filings related to Board proceedings before or after the Board has jurisdiction, such as:
   1. (1)Extensions during prosecution (see § 1.136 of this title),
   2. (2)Filing of a brief or request for oral hearing (see §§ 41.37, 41.41, 41.47, 41.67, 41.68, 41.71 and 41.73), or
   3. (3)Seeking judicial review (see §§ 1.301 to 1.304 of this title).