5 U.S.C. § 3581: Definitions

an Executive agency; a military department; and an employing authority in the legislative branch; “employee” means an employee in or under an agency; “international organization” means a public international organization or international-organization preparatory commission in which the Government of the United States participates; “transfer” means the change of position by an employee from an agency to an international organization; and the reemployment of an employee under section 3582(b) of this title ; or the reemployment of a Congressional employee within 90 days from his separation from an international organization;