37 C.F.R. §2.193(f)  Signature as certification.

The presentation to the Office (whether by signing, filing, submitting, or later advocating) of any document by any person, whether a practitioner or non-practitioner, constitutes a certification under §11.18(b) of this chapter.  Violations of §11.18(b) of this chapter may jeopardize the validity of the application or registration, and may result in the imposition of sanctions under §11.18(c) of this chapter.  Any practitioner violating §11.18(b) of this chapter may also be subject to disciplinary action.  See §§10.23(c)(15) [old rule] and 11.18(d) of this chapter.

37 C.F.R. §11.18  Signature and certificate for correspondence filed in the Office.

• (a) For all documents filed in the Office in patent, trademark, and other non-patent matters, and all documents filed with a hearing officer in a disciplinary proceeding, except for correspondence that is required to be signed by the applicant or party, each piece of correspondence filed by a practitioner in the Office must bear a signature, personally signed or inserted by such practitioner, in compliance with §1.4(d)(1), §1.4(d)(2), or §2.193(a) of this chapter.
• (b) By presenting to the Office or hearing officer in a disciplinary proceeding (whether by signing, filing, submitting, or later advocating) any paper, the party presenting such paper, whether a practitioner or non-practitioner, is certifying that—
• (1) All statements made therein of the party’s own knowledge are true, all statements made therein on information and belief are believed to be true, and all statements made therein are made with the knowledge that whoever, in any matter within the jurisdiction of the Office, knowingly and willfully falsifies, conceals, or covers up by any trick, scheme, or device a material fact, or knowingly and willfully makes any false, fictitious, or fraudulent statements or representations, or knowingly and willfully makes or uses any false writing or document knowing the same to contain any false, fictitious, or fraudulent statement or entry, shall be subject to the penalties set forth under 18 U.S.C. 1001 and any other applicable criminal statute, and violations of the provisions of this section may jeopardize the probative value of the paper; and
• (2) To the best of the party’s knowledge, information and belief, formed after an inquiry reasonable under the circumstances,
• (i) The paper is not being presented for any improper purpose, such as to harass someone or to cause unnecessary delay or needless increase in the cost of any proceeding before the Office;
• (ii) The other legal contentions therein are warranted by existing law or by a nonfrivolous argument for the extension, modification, or reversal of existing law or the establishment of new law;
• (iii) The allegations and other factual contentions have evidentiary support or, if specifically so identified, are likely to have evidentiary support after a reasonable opportunity for further investigation or discovery; and
• (iv) The denials of factual contentions are warranted on the evidence, or if specifically so identified, are reasonably based on a lack of information or belief.
• (c) Violations of any of paragraphs (b)(2)(i) through (iv) of this section are, after notice and reasonable opportunity to respond, subject to such sanctions or actions as deemed appropriate by the USPTO Director, which may include, but are not limited to, any combination of—
• (1) Striking the offending paper;
• (2) Referring a practitioner’s conduct to the Director of Enrollment and Discipline for appropriate action;
• (3) Precluding a party or practitioner from submitting a paper, or presenting or contesting an issue;
• (4) Affecting the weight given to the offending paper; or
• (5) Terminating the proceedings in the Office.
• (d) Any practitioner violating the provisions of this section may also be subject to disciplinary action.

37 C.F.R. §2.193  Trademark correspondence and signature requirements. (Extract)

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• (c) Requirements for electronic signature. A person signing a document electronically must:
• (1) Personally enter any combination of letters, numbers, spaces and/or punctuation marks that he or she has adopted as a signature, placed between two forward slash ("/") symbols in the signature block on the electronic submission; or
• (2) Sign the verified statement using some other form of electronic signature specified by the Director.
• (d) Signatory must be identified. The name of the person who signs a document in connection with a trademark application, registration, or proceeding before the Trademark Trial and Appeal Board must be set forth in printed or typed form immediately below or adjacent to the signature, or identified elsewhere in the filing (e.g., in a cover letter or other document that accompanies the filing).