22 U.S.C. § 6103
Separation of Government personnel during fellowships
Under such terms and conditions as the agency head may direct, any agency of the United States Government may separate from Government service for a specified period any officer or employee of that agency who accepts a fellowship under the program established by this chapter and is not detailed under section 6104 of this title.
Any fellow who is not a detailee, at the end of the fellowship, is entitled to be reemployed in the same manner as if covered by section 3582 of title 5.
Notwithstanding section 8347(o), 8713, or 8914 of title 5 and in accordance with regulations of the Office of Personnel Management, an employee, while serving as a fellow who is not a detailee, is entitled to the same rights and benefits as if covered by section 3582 of title 5. The Center shall reimburse the employing agency for any costs incurred under section 3582 of title 5.
Funds are available under this section to the extent and in the amounts provided in appropriation Acts.