33 CFR § 174.23 - Form of number.

---
identifier: "/us/cfr/t33/s174.23"
source: "ecfr"
legal_status: "authoritative_unofficial"
title: "33 CFR § 174.23 - Form of number."
title_number: 33
title_name: "Navigation and Navigable Waters"
section_number: "174.23"
section_name: "Form of number."
chapter_name: "COAST GUARD, DEPARTMENT OF HOMELAND SECURITY"
subchapter_number: "S"
subchapter_name: "BOATING SAFETY"
part_number: "174"
part_name: "STATE NUMBERING AND CASUALTY REPORTING SYSTEMS"
positive_law: false
currency: "2026-04-05"
last_updated: "2026-04-05"
format_version: "1.1.0"
generator: "[email protected]"
authority: "46 U.S.C. 6101 and 12302; DHS Delegation No. 00170.1, Revision No. 01.4."
regulatory_source: "CGD 72-54R, 37 FR 21402, Oct. 7, 1972, unless otherwise noted."
cfr_part: "174"
---


# 174.23 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.