5 CFR §359.202

Agency, Senior Executive Service position, senior executive, career appointee, limited emergency appointee, limited term appointee, and noncareer appointee, are defined in 5 U.S.C. 3132(a). Probation and probationary period mean the 1-year probation required by 5 U.S.C. 3393(d) upon initial career appointment to the SES. Reemployed annitant means an individual who is receiving an annuity under the Civil Service Retirement System or the Federal Employees' Retirement System on the basis of his or her former Federal service. A reemployed annuitant serves at the pleasure of the appointing authority.