CA Gov't Code Section 50022.2

Provided that all the procedures and requirements of this article are complied with, any local agency is hereby authorized to enact any ordinance which adopts any code by reference, in whole or in part; and such primary code, thus adopted, may in turn adopt by reference, in whole or in part, any secondary codes duly described therein. Every primary code which is incorporated in any such adopting ordinance shall be specified in the title of the ordinance. A local agency ordinance may adopt a code, the adoption of which is expressly required or permitted as a condition of compliance with a state statute, by reference without complying with the procedures and requirements of this article.