(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
After the commencement of an opposition, concurrent use, or interference proceeding, if the applicant files a written abandonment of the application or of the mark without the written consent of every adverse party to the proceeding, judgment shall be entered against the applicant. The written consent of an adverse party may be signed by the adverse party or by the adverse party's attorney or other authorized representative. 37 C.F.R. §2.135 54 FR 34900, Aug. 22, 1989 Part 3 pertaining to both patents