33 C.F.R. § 174.23 Form of number.
Title 33 - Navigation and Navigable Waters
(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.
Title 33: Navigation and Navigable Waters
PART 174—STATE NUMBERING AND CASUALTY REPORTING SYSTEMS
Subpart B—Numbering System Requirements
§ 174.23 Form of number.
