37 CFR 1.414 : Patents, Trademarks, And Copyrights (§ 1.1 To Chapter V) — (§ 1.1 To Chapter V) — United States Patent And Trademark Office, Department Of Commerce (§ 1.1 To Parts 151-199) — General (§ 1.1 To §§ 5.31-5.33) — Rules Of Practice In Patent Cases (§ 1.1 To § 1.1071) — International Processing Provisions (§ 1.401 To § 1.499) — General Information (§ 1.401 To § 1.419) — The United States Patent and Trademark Office as a Designated Office or Elected Office.

(a) The United States Patent and Trademark Office will act as a Designated Office or Elected Office for international applications in which the United States of America has been designated or elected as a State in which patent protection is desired.

(b) The United States Patent and Trademark Office, when acting as a Designated Office or Elected Office during international processing will be identified by the full title “United States Designated Office” or by the abbreviation “DO/US” or by the full title “United States Elected Office” or by the abbreviation “EO/US”.

(c) The major functions of the United States Designated Office or Elected Office in respect to international applications in which the United States of America has been designated or elected, include:

(1) Receiving various notifications throughout the international stage and

(2) National stage processing for international applications entering the national stage under 35 U.S.C. 371.