the exchange system
(a) Separate Systems .— The Secretary of Defense shall operate, in the manner provided by this chapter and other provisions of law, a world-wide system of commissary stores and a separate world-wide system of exchange stores. The stores of each system may sell, at reduced prices, food and other merchandise to members of the uniformed services on active duty, members of the uniformed services entitled to retired pay, dependents of such members, and persons authorized to use the system under chapter 54 of this title . Any reference in this chapter to “the exchange system” shall be treated as referring to each separate administrative entity within the Department of Defense through which the Secretary has implemented the requirement under this subsection for a world-wide system of exchange stores.