48 CFR 538.001: 538.001 General.

If a policy, regulation, or clause is identified as not applicable or in conflict to what is delegated by GSA, the delegated agency shall submit a determination and finding supporting the rationale as to why it does not apply, or is in conflict, in accordance with the delegation that was already received from GSA. The determination and finding must be approved by the GSA Senior Procurement Executive, the Commissioner of the Federal Acquisition Service (FAS) or a designee.