37 CFR § 41.40 - Tolling of time period to file a reply brief.
(a) Timing. Any request to seek review of the primary examiner's failure to designate a rejection as a new ground of rejection in an examiner's answer must be by way of a petition to the Director under § 1.181 of this title filed within two months from the entry of the examiner's answer and before the filing of any reply brief. Failure of appellant to timely file such a petition will constitute a waiver of any arguments that a rejection must be designated as a new ground of rejection.
(b) Petition granted and prosecution reopened. A decision granting a petition under § 1.181 to designate a new ground of rejection in an examiner's answer will provide a two-month time period in which appellant must file a reply under § 1.111 of this title to reopen the prosecution before the primary examiner. On failure to timely file a reply under § 1.111, the appeal will stand dismissed.
(c) Petition not granted and appeal maintained. A decision refusing to grant a petition under § 1.181 of this title to designate a new ground of rejection in an examiner's answer will provide a two-month time period in which appellant may file only a single reply brief under § 41.41.
(d) Withdrawal of petition and appeal maintained. If a reply brief under § 41.41 is filed within two months from the date of the examiner's answer and on or after the filing of a petition under § 1.181 to designate a new ground of rejection in an examiner's answer, but before a decision on the petition, the reply brief will be treated as a request to withdraw the petition and to maintain the appeal.
(e) Extensions of time. Extensions of time under § 1.136(a) of this title for patent applications are not applicable to the time period set forth in this section. See § 1.136(b) of this title for extensions of time to reply for patent applications and § 1.550(c) of this title for extensions of time to reply for ex parte reexamination proceedings.