49 CFR § 1500.5 - Rules of construction.

---
identifier: "/us/cfr/t49/s1500.5"
source: "ecfr"
legal_status: "authoritative_unofficial"
title: "49 CFR § 1500.5 - Rules of construction."
title_number: 49
title_name: "Transportation"
section_number: "1500.5"
section_name: "Rules of construction."
chapter_name: "TRANSPORTATION SECURITY ADMINISTRATION, DEPARTMENT OF HOMELAND SECURITY"
subchapter_number: "A"
subchapter_name: "ADMINISTRATIVE AND PROCEDURAL RULES"
part_number: "1500"
part_name: "APPLICABILITY, TERMS, AND ABBREVIATIONS"
positive_law: false
currency: "2026-03-24"
last_updated: "2026-03-24"
format_version: "1.1.0"
generator: "[email protected]"
authority: "49 U.S.C. 114, 5103, 40113, 44901-44907, 44913-44914, 44916-44918, 44935-44936, 44939, 44942, 46105; Pub. L. 110-53 (121 Stat. 266, Aug. 3, 2007) secs. 1408 (6 U.S.C. 1137), 1501 (6 U.S.C. 1151), 1517 (6 U.S.C. 1167), and 1534 (6 U.S.C. 1184)."
regulatory_source: "67 FR 8351, Feb. 22, 2002, unless otherwise noted."
cfr_part: "1500"
---


# 1500.5 Rules of construction.

(a) In this chapter, unless the context requires otherwise:

(1) Words importing the singular include the plural.

(2) Words importing the plural include the singular.

(3) Words importing the masculine sex include the feminine.

(b) In this chapter, the word:

(1) “Must” is used in an imperative sense;

(2) “May” is used in a permissive sense to state authority or permission to do the act prescribed, and the words “no person may * * *” or “a person may not * * *” mean that no person is required, authorized, or permitted to do the act prescribed; and

(3) “Includes” means “includes but is not limited to”.

[67 FR 8351, Feb. 22, 2002, as amended at 90 FR 21690, May 21, 2025]