14 CFR 89.505: Serial numbers.

No person may produce a standard remote identification unmanned aircraft under § 89.510 or § 89.515 or a remote identification broadcast module under § 89.520, unless the producer assigns to the unmanned aircraft or remote identification broadcast module a serial number that complies with ANSI/CTA-2063-A. ANSI/CTA-2063-A, Small Unmanned Aerial Systems Serial Numbers (September 2019) is incorporated by reference into this section with the approval of the Director of the Office of the Federal Register under 5 U.S.C. 552(a) and 1 CFR part 51. All approved material is available for inspection at the FAA's Office of Rulemaking (ARM-1), 800 Independence Avenue SW, Washington, DC 20590 (telephone 202-267-9677) and is available from Consumer Technology Association (CTA), 1919 South Eads Street, Arlington, VA 22202, CTA@CTA.tech, 703-907-7600 or at https://www.cta.tech. It is also available for inspection at the National Archives and Records Administration (NARA). For information on the availability of this material at NARA, email fedreg.legal@nara.gov, or go to www.archives.gov/federal-register/cfr/ibr-locations.html.