CFR > Title 49 - Transportation > SUBTITLE B—Other Regulations Relating to Transportation > CHAPTER I—PIPELINE AND HAZARDOUS MATERIALS SAFETY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION (Parts 105–199) > SUBCHAPTER C—HAZARDOUS MATERIALS REGULATIONS (Parts 171–181) > PART 171—GENERAL INFORMATION, REGULATIONS, AND DEFINITIONS > SUBPART A—Applicability, General Requirements, and North American Shipments (§171.1 to §171.14) > 171.9—Rules of construction.

171.9—Rules of construction.

(a) In this subchapter, unless the context requires otherwise:
(1) Words imparting the singular include the plural;
(2) Words imparting the plural include the singular; and
(3) Words imparting the masculine gender include the feminine;
(b) In this subchapter, the word: (1) “Shall” is used in an imperative sense;
(2) “Must” is used in an imperative sense;
(3) “Should” is used in a recommendatory sense;
(4) “May” is used in a permissive sense to state authority or permission to do the act described, and the words “no person may * * *” or “a person may not * * *” means that no person is required, authorized, or permitted to do the act described; and
(5) “Includes” is used as a word of inclusion not limitation.
[Amdt. 171-32, 41 FR 15996, Apr. 15, 1976, as amended by Amdt. 171-32A, 41 FR 40630, Sept. 20, 1976; Amdt. 171-121, 58 FR 51528, Oct. 1, 1993; 75 FR 60338, Sept. 30, 2010]