33 CFR 174.23 : Navigation And Navigable Waters (§ 1.01-1 To Parts 404-499) — (§ 125.01 To Parts 188-199) — Coast Guard, Department Of Homeland Security (Continued) (§ 125.01 To Parts 188-199) — Boating Safety (§ 173.1 To Parts 188-199) — State Numbering And Casualty Reporting Systems (§ 174.1 To § 174.125) — Numbering System Requirements (§ 174.11 To § 174.31) — Form of number.

(a) Each number must consist of two capital letters denoting the State of the issuing authority, as specified in Appendix A of Part 173 of this chapter, followed by -

(1) Not more than four numerals followed by not more than two capital letters (example: NH 1234 BD); or

(2) Not more than three numerals followed by not more than three capital letters (example: WN 567 EFG).

(b) A number suffix must not include the letters “I”, “O”, or “Q,” which may be mistaken for numerals.