[Code of Federal Regulations] [Title 49, Volume 8] [Revised as of October 1, 2004] From the U.S. Government Printing Office via GPO Access [CITE: 49CFR1500.5] [Page 245] TITLE 49--TRANSPORTATION CHAPTER XII--TRANSPORTATION SECURITY ADMINISTRATION, DEPARTMENT OF HOMELAND SECURITY PART 1500_APPLICABILITY, TERMS, AND ABBREVIATIONS--Table of Contents Sec. 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 gender 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''.