CFR /  Title 49  /  Part 390  /  Sec. 390.7 Rules of construction.

(a) In part 325 of subchapter A and in this subchapter, unless the context requires otherwise:

(1) Words imparting the singular include the plural;

(2) Words imparting the plural include the singular;

(3) Words imparting the present tense include the future tense.

(b) In this subchapter the word--

(1) Officer includes any person authorized by law to perform the duties of the office;

(2) Writing includes printing and typewriting;

(3) Shall is used in an imperative sense;

(4) Must is used in an imperative sense;

(5) Should is used in a recommendatory sense;

(6) May is used in a permissive sense; and

(7) Includes is used as a word of inclusion, not limitation. [53 FR 18052, May 19, 1988, as amended at 60 FR 38744, July 28, 1995]