(1) Subject to the following and all other provisions of this chapter, including such rules and regulations as the board shall adopt in pursuance thereof, the board, subject to the approval of the city council or city commission, shall determine and may modify allowance for service.

Time during which a member is absent on leave without pay shall not be allowed in computing service: PROVIDED, HOWEVER, That any member shall be given credit for any period served by him or her in the national guard, or in the United States army, navy, or marine corps, upon the call of the president, if at the time of such service such member was a regular employee under leave of absence. Certificate of honorable discharge from and/or documentary evidence of such service shall be submitted to the board in order to obtain credit for such service.

Each member shall file with the board such information affecting his or her status as a member of the retirement system as the board may require.

(2) The board shall grant credit for prior service to each member entering the retirement system on July 1, 1939, and to each member entering after that date, if such entry is within one year after rendering service prior to July 1, 1939: PROVIDED, HOWEVER, That the board may grant credit for prior service to those entering the retirement system after July 1, 1939, where the employee, because of sickness or other disability, has been on leave of absence, regularly granted, since discontinuance of city service, regardless of the length of such leave. No prior service credit shall be used as a basis for retirement or other benefit unless the membership continues until retirement on a retirement allowance or until the granting of other benefits.