(a) Any member of the organized militia who has reached the age of 64 years shall be retired for the reason of age and shall be transferred to the state retired list by the Governor. A member may be retired for reason of age and transferred to the state retired list by the Governor before reaching 64 years of age in order to conform to the laws and regulations of the United States which are applicable to the organized militia.

(b) Any officer who has served for at least 20 years in the organized militia or in the organized militia and the armed forces of the United States combined, upon his request, may be transferred to the state retired list by the Governor in a grade which is one grade higher than the highest grade previously held by him during such service. In computing the 20 year period, service as an enlisted person shall be counted.

(c) Any warrant officer or enlisted person who has served for at least 20 years in the organized militia or in the organized militia and the armed forces of the United States combined, upon his request, may be transferred to the state retired list by the Governor in a grade equivalent to the highest grade held by him during such service. If the grade was of officer grade, subsection (b) of this Code section will govern.

(d) Upon the recommendation of the adjutant general, the Governor may order any person on the state retired list to return to active duty and serve on military courts or boards, perform staff duty in or with the organized militia, or, in time of emergency, perform any military duty in or with the organized militia. In any such case, the person so ordered shall rank in his grade at retirement from the date of the order.

(e) Time spent on the state retired list shall not be credited in the computation of length of service for seniority, pay, promotion, or otherwise, or any of the privileges and exemptions pertaining thereto, except that time served on active duty by order of the Governor shall be credited.