5 C.F.R. § 8.2
United States citizens may be recruited overseas for appointment to overseas positions in the competitive service without regard to the competitive requirements of the Civil Service Act. Persons so recruited who meet the qualification standards and other requirements of OPM for overseas positions may be given appointments to be known as "overseas limited appointments." Such appointments shall be of temporary or indefinite duration, and shall not confer the right to acquire a competitive status. OPM may authorize overseas limited appointments for United States citizens recruited within the continental limits of the United States whenever it determines that it is not feasible to appoint from a civil-service register. Persons serving under appointments made pursuant to this section are hereby excluded from the operation of the Civil Service Retirement Act of May 29, 1930, as amended, unless eligible for retirement benefits by continuity of service or otherwise.
5 C.F.R. § 8.2