5 U.S.C. § 5331

(a) For the purpose of this subchapter, “agency”, “employee”, “position”, “class”, and “grade” have the meanings given them by section 5102 of this title . (b) This subchapter applies to employees and positions to which chapter 51 applies, other than Senior Executive Service positions, positions in the Federal Bureau of Investigation and Drug Enforcement Administration Senior Executive Service, and positions to which section 5376 applies.