10 U.S.C. § 2492 : US Code - Section 2492: Nonappropriated fund instrumentalities: contracts with other agencies and instrumentalities to provide and obtain goods and services

      An agency or instrumentality of the Department of Defense that
    supports the operation of the exchange system, or the operation of
    a morale, welfare, and recreation system, of the Department of
    Defense may enter into a contract or other agreement with another
    element of the Department of Defense or with another Federal
    department, agency, or instrumentality to provide or obtain goods
    and services beneficial to the efficient management and operation
    of the exchange system or that morale, welfare, and recreation
    system.