(a) This subpart implements 5 U.S.C. 5376 and applies to—

(1) Senior-level (SL) positions classified above GS-15 pursuant to 5 U.S.C. 5108; and

(2) Scientific or professional (ST) positions established under 5 U.S.C. 3104.

(b) This subpart does not apply to—

(1) Senior Executive Service positions established under 5 U.S.C. 3132,unless,under.303 of this chapter, remained at grade GS-16, 17, or 18 (now the SL pay system) or under the ST pay system;

(2) Positions in the Federal Bureau of Investigation and Drug Enforcement Administration Senior Executive Service, Defense Intelligence Executive Service, or Senior Cryptologic Executive Service; or

(3) Positions for which pay is fixed by administrative action and is limited to level IV of the Executive Schedule under 5 U.S.C. 5373.