Executive Order 10000: Regulations Governing Additional Compensation and Credit Granted Certain Employees of the Federal Government Serving Outside the United States [open html - 40KB]
"By virtue of the authority vested in me by section 207 of the Independent Offices Appropriation Act, 1949, approved April 20, 1948 (Public Law 491, 80th Congress), as amended by section 104 of the Supplemental Independent Offices Appropriation Act, 1949, approved June 30, 1948 (Public Law 862, 80th Congress), and by sections 303, 443, and 853 of the Foreign Service Act of 1946 (60 Stat. 1002, 1006, 1024), and as President of the United States, I hereby prescribe the following regulations (1) governing the payment of additional compensation to personnel of the United States employed outside the continental United States or in Alaska, under the provisions of the said section 207, as amended, (2) governing the payment of salary differentials to Foreign Service staff officers and employees serving at certain posts, pursuant to the said section 443, and (3) relating to unhealthful foreign posts, pursuant to the said section 853[.]"
Executive Order 10000; EO 10000
National Archives: https://www.archives.gov/
13 FR 5453, 6075, 3 CFR, 1943-1948 Comp., p. 792