PUBLIC LAWS-CH. 393-AUG. 4 , 1949 Sec. 367. Detention beyond term of enlistment. 368. Discharge in case of under-age enlistment. 369. Inclusion of certain conditions in enlistment contract. GENERAL PROVISIONS 421. Retirement. 422. Status of recalled personnel. 423. Computation of retired pay. 424. Limitations on retirement and retired pay. 425. Retiring boards. SPECIAL PROVISIONS 431. Personnel of former Life Saving Service. 432. Personnel of former Lighthouse Service. 433. Personnel of former Bureau of Marine Inspection and Navigation and Bureau of Customs. COMMISSIONED OFFICERS § 221. Filling of vacancies Whenever a vacancy occurs in the active list of regular commissioned officers, in the grade of ensign or above, which the Secretary determines shall be filled, such vacancy shall be filled either by promotion through appointment by the President to a higher grade as hereinafter pro- vided or by appointment by the President from among the groups set Poe, p. 513. forth in section 225 of this title. § 222. Promotion of officers to flag rank Commissioned officers, including extra numbers in grade, shall be promoted to the grade of rear admiral by selection, under such regula- tions as the Secretary shall prescribe. The precedence on the list of rear admirals shall be determined by the date of first appointment to that grade, except that the Assistant Commandant shall, while holding such office, be next in precedence to the Commandant. § 223. Filling of vacancies by promotion (a) When a vacancy below the grade of rear admiral is to be filled by promotion as determined by the Secretary, the senior officer of the next lower grade, not out of line of promotion, shall be appointed by the President, by and with the advice and consent of the Senate, to fill such vacancy as of the date such vacancy occurred. No commissioned officer shall be promoted to a higher grade on the active list until his mental, moral, and professional fitness to perform the duties of such higher grade have been established to the satisfaction of the Secretary and until he has been pronounced physically qualified to perform the duties of such higher grade. (b) The Secretary may prescribe regulations dealing with the filling of vacancies by promotion, including, but not limited to, the scope and method of conducting professional and physical examinations, the number of re-examinations permitted, the circumstances under which an officer may be excused from being examined in a particular subject, and the passing marks required; and dealing with the placing of officers out of, and the restoring of officers to, the line of promotion. (c) An ensign who has completed three years' service in his grade shall be eligible for promotion to lieutenant (junior grade) if he is qualified therefor in accordance with such regulations as the Secretary shall prescribe. § 224. Filling of vacancies by appointment (a) Vacancies in the grade of captain and below may be filled by appointment. When a vacancy is to be filled by appointment thereto [63 STAT.