(A) Provision shall be made that the Board shall determine how much service shall be credited any member; provided, that in no case shall less than ten days of service rendered in any calendar month be credited as a month of service, nor shall less than nine months of service rendered in any calendar year be credited as a year of service, nor shall more than one year of service be credited any member for all service rendered by him in any calendar year.
(B) The Board shall give a member service credit for the period served by him in the Armed Forces of the United States during time of war or other national emergency; provided, that (1) he was a city employee at the time he entered or enters the said Armed Forces, and (2) he reentered or reenters city employment within at least 18 months following termination of such armed service required of him.