California Code, Revenue and Taxation Code - RTC § 2262

(1) For general law cities, the aggregate of all citywide property tax rates which were levied for general city purposes in either the 1971-1972 or the 1972-1973 fiscal year, at the option of the city council;  provided that if the aggregate of such property tax rates was less than one dollar ($1) in both the 1971-1972 and the 1972-1973 fiscal years, the maximum property tax rate for such cities shall be one dollar ($1).  In addition, any property tax rate authorized by the voters of a city as provided in Section 43068 of the Government Code which was not levied as part of the aggregate of citywide taxes in the fiscal year selected by the city council pursuant to this subdivision may also be levied.

(2) For charter cities, the maximum rate, or rates, specified in the charter;  provided that any rate in excess of such maximum rate which is authorized by Section 43072 of the Government Code or by Section 35 of Chapter 1 of the Statutes of 1968 (First Extraordinary Session) and which was levied during either the 1971-1972 or the 1972-1973 fiscal year may continue to be levied.  If no maximum rate is specified in the charter, or if a maximum rate is specified but such rate is applicable only to a portion of the purposes for which such city is levying an ad valorem property tax, the maximum rate shall be the rate levied by the city for either the 1971-1972 or the 1972-1973 fiscal year, at the option of the city council.  In addition, if the voters of a charter city, pursuant to provisions of the charter or of general law, have authorized an additional rate, such augmented rate shall be the maximum property tax rate.