(a) (1) The testimony of witnesses in inter partes cases may be submitted in the form of an affidavit or a declaration pursuant to § 2.20 and in conformance with the Federal Rules of Evidence, filed during the proffering party's testimony period, subject to the right of any adverse party to elect to take and bear the expense of oral cross-examination of that witness as provided under paragraph (c) of this section if such witness is within the jurisdiction of the United States, or conduct cross-examination
(a) Except for the notice of opposition or the petition to cancel, every submission filed in the Office in inter partes cases, including notices of appeal to the courts, must be served upon the other party or parties. Proof of such service must be made before the submission will be considered by the Office. A statement signed by the attorney or other authorized representative, attached to or appearing on the original submission when filed, clearly stating the date and manner in which service was