37 CFR 2.191 - Business to be transacted in writing.
All business with the Office should be transacted in writing. The personal appearance of applicants or their representatives at the Office is unnecessary. The action of the Office will be based exclusively on the written record. No attention will be paid to any alleged oral promise, stipulation, or understanding in relation to which there is disagreement or doubt. The Office encourages parties to file documents through TEAS wherever possible, and mandates that documents in proceedings before the Trademark Trial and Appeal Board be filed through ESTTA.