---
kind: "section"
citation: "33 C.F.R. § 174.23"
title: "33"
number: "174.23"
heading: "Form of number."
url: "https://uscodex.org/cfr/33/174.23"
---

# §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](/cfr/33/part173.md) 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.

## Notes

### Authority

Authority: 46 U.S.C. 6101 and 12302; DHS Delegation No. 00170.1, Revision No. 01.4.

### Source

Source: CGD 72-54R, 37 FR 21402, Oct. 7, 1972, unless otherwise noted.