Education Code § 24701
CHAPTER 32. San Francisco Local System
Those credentialed members of the San Francisco Employees’ Retirement System on June 30, 1972, who make an irrevocable election to be covered only by the State Teachers’ Retirement Plan under this part for prior and future service performed in San Francisco, shall be allowed to be covered for other certificated service concurrently, where the provisions of the city and county charter permit. This shall not include any credited service, as defined in Section 22121.