41 C.F.R. § 101-26.100

This subpart provides policy guidance of a general nature concerning procurement of lowest cost items obtainable from GSA supply sources; availability from GSA of special buying services in addition to the specified GSA procurement sources; criteria for placing end-of-year purchase documents with GSA and for insuring that end-of-year requisitions placed with GSA obligate the applicable fiscal year appropriation; and justification requirements to support negotiated procurement by GSA for other agencies.