37 C.F.R. § 2.133 : Patents, Trademarks, and Copyrights — UNITED STATES PATENT AND TRADEMARK OFFICE, DEPARTMENT OF COMMERCE — GENERAL — RULES OF PRACTICE IN TRADEMARK CASES —PROCEDURE IN INTER PARTES PROCEEDINGS — Amendment of application or registration during proceedings

(a) An application subject to an opposition may not be amended in substance nor may a registration subject to a cancellation be amended or disclaimed in part, except with the consent of the other party or parties and the approval of the Trademark Trial and Appeal Board, or upon motion granted by the Board.
(b) If, in an inter partes proceeding, the Trademark Trial and Appeal Board finds that a party whose application or registration is the subject of the proceeding is not entitled to registration in the absence of a specified restriction to the application or registration, the Board will allow the party time in which to file a motion that the application or registration be amended to conform to the findings of the Board, failing which judgment will be entered against the party.
(c) Geographic limitations will be considered and determined by the Trademark Trial and Appeal Board only in the context of a concurrent use registration proceeding.
(d) A plaintiff's pleaded registration will not be restricted in the absence of a counterclaim to cancel the registration in whole or in part, except that a counterclaim need not be filed if the registration is the subject of another proceeding between the same parties or anyone in privity therewith.

37 C.F.R. §2.133

54 FR 37597, 9/11/1989, as amended at 72 FR 42263, 8/1/2007