Cal. Elec. Code § 9256

The proponents of a measure proposing to amend a charter shall publish or post, or both, a notice of intent to circulate the petition in the same form and manner as prescribed in Sections 9202, 9203, 9204, and 9205. The proponents shall also file an affidavit prescribed in Section 9206 with the clerk of the legislative body of the city, and, with respect to the petition, shall be subject to Section 9207.