To be an official act of the officer promotion board, an act of that board must be approved by not less than four of the members of the board: PROVIDED, HOWEVER, That if the board consists of less than four officers, the approval of the board shall be unanimous.

An action of an officer promotion board may be an official act of the board without a meeting if all members of the board approve in writing the act in question.

The adjutant general will from time to time fix the rules under which the board will operate.