22 USC 3972 - Special differentials

(a) Additional work requirements 
The Secretary may pay special differentials, in addition to compensation otherwise authorized, to Foreign Service officers who are required because of the nature of their assignments to perform additional work on a regular basis in substantial excess of normal requirements.
(b) Repealed. Pub. L. 103–236, title I, § 139(6), Apr. 30, 1994, 108 Stat. 398 
(c) Compensatory time off 
Nothing in this chapter, or in subchapter V of chapter 55 of title 5 shall preclude the granting of compensatory time off for Foreign Service officers.