(a) Each employee in service on December 31, 1943, or then on leave of absence not in conflict with Civil Service rules, if such leave had not extended for more than one year continuously, or who is otherwise entitled to prior service credit, who becomes a member shall file with the board on a form supplied by it, a detailed statement of all service rendered prior to January 1, 1944, for which credit is claimed.
Upon verification thereof, the board shall issue a prior service certificate certifying length of prior service. A prior service certificate shall be conclusive so long as membership continues, provided, that a member may, within one year from the date of original issuance of the certificate or modification thereof, request the board to modify or correct the certificate.
When membership ceases, a prior service certificate shall become void, and shall be revived only under the conditions specified in this Article.
In the computation of prior service, the following schedule shall govern: 9 months of service or more during any fiscal year constitutes a year of service; 6 to 9 months, 3/4 of a year; 3 to 6 months, 1/2 year; less than 3 months shall not be considered. Credit shall not be allowed for any period of absence without compensation or for less than 15 days service in any month, nor shall more than one year of service be creditable for all service rendered in any one fiscal year.