Cal. Gov. Code § 45310.5
The ordinance may provide for a modification of rights and benefits of a member because of membership in a reciprocal system similar to and under the same conditions as those provided under the County Employees' Retirement Law of 1937 and the Public Employees' Retirement Law because of membership in two or more retirement systems established by or pursuant to such laws. The ordinance shall be filed with each board administering a reciprocal system and shall become effective upon the adoption of a resolution of such administering board accepting the city system as a reciprocal system. Such modification shall apply only to a member whose termination and entry into employment resulting in a change in membership from the city system to a reciprocal system or from a reciprocal system to the city system occurs after such effective date; provided, however, that provisions relating to computation of final compensation shall apply to any other member if such provision would have applied had the termination and entry into employment occurred after such effective date.
A reciprocal system, for purposes of this section, means a retirement system established under the County Employees' Retirement Law of 1937, the Public Employees' Retirement System, a retirement system of a city whose retirement ordinance contains the provisions authorized by this section, or a retirement system of a city or city and county established by its charter and providing for modifications of rights and benefits similar to and under the same conditions as those provided for under this section.
When a city has established a reciprocal retirement system under this section and has received approval thereof from the Public Employees' Retirement System, then such system shall be automatically reciprocal with all other state, local and public agencies who are members, or contracting members of the Public Employees' Retirement System or any retirement system established under the County Employees Retirement Law of 1937.
Ca. Gov. Code § 45310.5