The director of personnel shall keep in the personnel office an official roster of all persons holding positions under this part and shall enter thereon the name of each person who has been appointed to, promoted, reduced, transferred, reinstated, or removed from or left any position and require such evidence as may be deemed satisfactory as to whether such person was appointed to, promoted, reduced, transferred, reinstated, or removed from such position in accordance with this part and the rules and regulations of the personnel board thereunder, and as to when and why and how such action was taken. The official roster shall show opposite or in connection with each name of appointment, promotion, reduction, transfer, or reinstatement, rate of compensation of the position, the date of commencement of service, and change in or separation from position, and when and why and how such change or separation occurred. The director may prescribe the manner, forms, and procedures necessary to establish and maintain such employment history.