Cal. Gov. Code § 51949

Upon reorganization, the charter of the city-county shall have full effect throughout the city-county. The charter shall recognize the status of each of the other cities which have voted to retain their local governmental structure pursuant to Article 3 or their governmental independence pursuant to Article 3.5, whichever is applicable. The charter may provide for subgovernments, different tax rates, and other differences in taxation, services, costs of government and levels of service, and type of government representation and administration in different areas of the city-county.