A requirement is a description of an agency's need, and includes the appropriated funds to satisfy the needs. To the maximum extent practicable, acquisition officials should ensure that requirements are defined in terms of the functions to be performed, the performance required, or essential physical characteristics. (FAR Part 11 prescribes policies and procedures for describing agency needs.)
FAR Subpart 11.6 -- Priorities and Allocations implements the Defense Priorities and Allocation System (DPAS), a Department of Commerce regulation in support of approved national defense, emergency preparedness, and energy programs (see 15 CFR part 700).