1976 - Subsec. (b). Pub. L. 94-489 substituted provision defining service employees to include all employees, but excluding bona fide executive, administrative, and professional employees, for provision defining service employees as guards, watchmen, any person engaged in a recognized trade or craft, or in unskilled, semiskilled, or skilled manual labor occupations; and any other employee including a foreman or supervisor in a position having trade, craft, or laboring experience as the paramount requirement. 1973 - Subsec. (d). Pub. L. 93-57 defined ''United States'' to include Canton Island.

Section 2 of Pub. L. 93-57 provided that: ''The amendment made hereby (amending this section) shall be effective with respect to all contracts entered into at any time after the date of enactment (July 6, 1973).''