---
kind: "section"
citation: "49 C.F.R. § 193.2009"
title: "49"
number: "193.2009"
heading: "Rules of regulatory construction."
url: "https://uscodex.org/cfr/49/193.2009"
---

# §193.2009. Rules of regulatory construction.

- (a) **As used in this part—**
  - (1) Includes means including but not limited to;
  - (2) May means is permitted to or is authorized to;
  - (3) May not means is not permitted to or is not authorized to; and
  - (4) **Shall—** or must is used in the mandatory and imperative sense.
- (b) **In this part—**
  - (1) Words importing the singular include the plural; and
  - (2) **Words importing the plural include the singular.**

## Notes

### Authority

Authority: 49 U.S.C. 5103, 60102, 60103, 60104, 60108, 60109, 60110, 60113, 60118; and 49 CFR 1.53.

### Source

Source: 45 FR 9203, Feb. 11, 1980, unless otherwise noted.