37 CFR 2.42 : Patents, Trademarks, And Copyrights (Section 2.11 To Chapter V) — United States Patent And Trademark Office, Department Of Commerce (Parts 1 - 199) (Section 2.11 To Parts 151-199) — Unknown Title (Parts 2 - 90) (Section 2.11 To Section 90.3) — Rules Of Practice In Trademark Cases (Section 2.11 To Section 2.7) — Representation By Attorneys Or Other Authorized Persons (Part 2) (Section 2.11 To Section 2.209) — Concurrent use.

An application for registration as a lawful concurrent user shall specify and contain all the elements required by the preceding sections. The applicant in addition shall state in the application the area, the goods, and the mode of use for which applicant seeks registration; and also shall state, to the extent of the applicant's knowledge, the concurrent lawful use of the mark by others, setting forth their names and addresses; registrations issued to or applications filed by such others, if any; the areas of such use; the goods on or in connection with which such use is made; the mode of such use; and the periods of such use.