60 STAT.] 79TH CONG. , 2D SESS.-CH. 957-AUG. 13, 1946 or employees while serving under consular commissions in the Service shall be performed under their respective commissions as consular officers. CITIZENSHIP REQUIREMENT SEC. 534. No person shall be eligible for appointment as staff officer or employee who is not a citizen of the United States at the time of his appointment. PART E-A--IEN CLERKS AND EMPLOYEE8 APPOINTMENTS SEC. 541. The Secretary shall appoint alien clerks and employees at posts abroad under such regulations as he may prescribe and, as soon as practicable, in accordance with the provisions of section 444. ASSIGNMENTS AND TRANSFERS Sea. 542. The Secretary may assign an alien clerk or employee to a position at any post, and any such clerk or employee may be transferred from a position at one post to a position at another as the interests of the Service may require. PART F-CONSULAR AGENTS SEC. 551. The Secretary may appoint consular agents under such regulations as he may prescribe and, as soon as practicable, in accord- ance with the provisions of section 445. PART G--ASSIGNMENT OF PERSONNE BY TMHE WAR AND NAVY DEPARTMENTS AS COURIERS AND INSPECTORS OF BUTDINGS SEC. 561. The Secretaries of War and Navy are authorized, upon the request of the Secretary, to assign or detail military and naval per- sonnel serving under their supervision for duty as inspectors of build- ings owned or occupied abroad by the United States or as inspectors or supervisors of buildings under construction or repair abroad by or for the United States, or for duty as couriers of the Department; and, when so assigned or detailed, they may receive the same traveling expenses as are authorized for officers of the Service, payable from applicable appropriations of the Department. Such assignments or details may, in the discretion of the head of the department concerned, be made without reimbursement from the Department of State. AS CUSTODIANS SEz. 562. The Secretary of the Navy is authorized, upon request of the Secretary of State, to assign enlisted men of the Navy and the Marine Corps to serve as custodians under the supervision of the prin- cipal officer at an embassy, legation, or consulate. PABT H-ASSIGNMENT OF FoEEIGN SERVICE PERSONNIL ASSIGNMENTS TO ANY GOVERNMENT AGENCY SBO. 571. (a) Any officer or employee of the Service may, in the discretion of the Director General, be assigned or detailed for duty in any Government agency, such an assignment or combination of assignments to be for a period of not more than four years. He may not again be assigned for duty in a Government agency until the expiration of a period of time equal to his preceding tour of duty on 1011 Ante, p. 1006 . Ante, p. 1006 Trveling eupense. Beassignment.