; exceptions The provisions of section 619a of this title shall apply to officers of the Space Force. 20233. Opportunities for consideration for promotion (a) Specification of number of opportunities for consideration for promotion Under regulations prescribed by the Secretary of Defense, the Secretary of the Air Force shall specify the number of opportunities for consideration for promotion to be afforded to Space Force officers for promotion to each grade above the grade of captain. (b) Limitation on number of opportunities that may be specified The number of opportunities for consideration for promotion to be afforded officers of the Space Force for promotion to a particular grade may not exceed five. (c) Limited authority of secretary of the air force To modify number of opportunities The Secretary of the Air Force may change the number of opportunities for consideration for promotion to a particular grade not more frequently than once every five years. (d) Authority of secretary of defense To modify number of opportunities The Secretary of Defense may modify the number of opportunities for consideration for promotion to be afforded officers of the Space Force for promotion to a particular grade. 20234. Space Force officer list (a) Single list The Secretary of the Air Force shall maintain a single list of all Space Force officers serving in a Space Force active status. The list shall be known as the Space Force officer list. (b) Order of officers on list Officers shall be carried on the Space Force officer list in the order of seniority of the grade in which they are serving. Officers serving in the same grade shall be carried in the order of their rank in that grade. (c) Effect of service in a temporary appointment An officer whose position on the Space Force officer list results from service under a temporary appointment or in a grade held by reason of assignment to a position has, when that appointment or assignment ends, the grade and position on the Space Force officer list that the officer would have