(a) The term “Department of the Army” as used in this chapter shall be construed to mean the Department of the Army at the seat of the government and all field headquarters, forces, reserve components, installations, activities, and functions under the control or supervision of the Department of the Army.

(b) The term “Department of the Navy” as used in this chapter shall be construed to mean the Department of the Navy at the seat of the government; the headquarters, United States Marine Corps; the entire operating forces of the United States Navy, including naval aviation, and of the United States Marine Corps, including the reserve components of such forces; all field activities, headquarters, forces, bases, installations, activities, and functions under the control or supervision of the Department of the Navy; and the United States Coast Guard when operating as a part of the Navy pursuant to law.

(c) The term “Department of the Air Force” as used in this chapter shall be construed to mean the Department of the Air Force at the seat of the government and all field headquarters, forces, reserve components, installations, activities, and functions under the control or supervision of the Department of the Air Force.