597 (B) is trained, and has its officers appointed, under the sixteenth clause of section 8, article I, of the Constitution; (C) is organized, armed, and equipped wholly or partly at Federal expense; and (D) is federally recognized. (6) "Air National Guard of the United States" means the reserve component of the Air Force all of whose members are members of the Air National Guard. (7) "Officer" means commissioned or warrant officer. (8) "Enlisted member" means a person enlisted in, or inducted, called, or conscripted into, an armed force in an enlisted grade. (9) "Grade" means a step or degree, in a graduated scale of office or military rank, that is established and designated as a grade by law or regulation. (10) "Rank" means the order of precedence among members of the armed forces. (11) "Active duty" means full-time duty in the active military service of the United States. It includes such Federal duty as duty on the active list, full-time training duty, annual training duty, and attendance, while in the active military service, at a school designated as a service school by law or by the Secretary of the military department concerned. (12) "Supplies" includes material, equipment, and stores of all kinds. (13) "Shall" is used in an imperative sense. (14) "May" is used in a permissive sense. The words "no person may..." mean that no person is required, authorized, or permitted to do the act prescribed. (15) "Includes" means "includes but is not limited to". (16) "Pay" includes basic pay, special pay, incentive pay, retired pay, and equivalent pay, but does not include allowances, § 102. General policy In accordance with the traditional military policy of the United States, it is essential that the strength and organization of the Army National Guard and the Air National Guard as an integral part of the first line defenses of the United States be maintained and assured at all times. Whenever Congress determines that more units and organizations are needed for the national security than are in the regular components of the ground and air forces, the Army National Guard of the United States and the Air National Guard of the United States, or such parts of them as are needed, together with such units of other reserve components as are necessary for a balanced force^ shall be ordered to active Federal duty and retained as long as so needed. § 103. Branches and organizations The Army National Guard of each State and Territory, Puerto Rico, the Canal Zone, and the District of Columbia includes such members of the staff corps corresponding to the staff corps of the Army as the Secretary of the Army may authorize.