48 C.F.R. § 44.101
As used in this part-
Approved purchasing system means a contractor's purchasing system that has been reviewed and approved in accordance with this part.
Contractor means the total contractor organization or a separate entity of it, such as an affiliate, division, or plant, that performs its own purchasing.
Contractor purchasing system review (CPSR) means the complete evaluation of a contractor's purchasing of material and services, subcontracting, and subcontract management from development of the requirement through completion of subcontract performance.
Subcontract means any contract as defined in subpart 2.1 entered into by a subcontractor to furnish supplies or services for performance of a prime contract or a subcontract. It includes but is not limited to purchase orders, and changes and modifications to purchase orders.
Subcontractor means any supplier, distributor, vendor, or firm that furnishes supplies or services to or for a prime contractor or another subcontractor.
48 C.F.R. §44.101