[Code of Federal Regulations] [Title 49, Volume 5] [Revised as of October 1, 2007] From the U.S. Government Printing Office via GPO Access [CITE: 49CFR390.7] [Page 318-319] TITLE 49--TRANSPORTATION DEPARTMENT OF TRANSPORTATION PART 390_FEDERAL MOTOR CARRIER SAFETY REGULATIONS; GENERAL--Table of Contents Subpart A_General Applicability and Definitions 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; [[Page 319]] (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]