This subpart does not apply to—

(a) Requirements that an 8(a) contractor is currently performing under the 8(a) program or that SBA has accepted for performance under the authority of the 8(a) program, unless SBA has consented to release the requirements from the 8(a) program;

(b) Requirements that can be satisfied through award to mandatory Government sources (see section 8.002);

(c) Orders under indefinite-delivery contracts (see subpart 16.5). (But see 16.505(b)(2)(i)(F) for discretionary set-asides of orders); or

(d) Orders against Federal Supply Schedules (see subpart 8.4). (But see 8.405-5 for discretionary set-asides of orders.)