Code of Federal Regulations Title 49. Transportation § 49.1500.5 Rules of construction

(1) Words importing the singular include the plural.

(2) Words importing the plural include the singular.

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

(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”.