California Code, Elections Code - ELEC § 100

(a) Notwithstanding any other provision of law, whenever an initiative, referendum, recall, nominating petition or paper, or any other petition or paper is required to be signed by voters of a county, city, school district, or special district subject to petitioning, only a person who is an eligible registered voter at the time of signing the petition or paper is entitled to sign the petition or paper. A person who submits their affidavit of registration pursuant to subdivision (d) of Section 2102 is not eligible to sign a petition or paper unless at the time of the signing of the petition or paper that person is 18 years of age.

(b) A signer shall at the time of signing the petition or paper personally affix their signature, printed name, and place of residence, including the street and number of the place of residence, and if no street or number for the place of residence exists, then a designation of the place of residence that will enable the location to be readily ascertained. An incomplete or inaccurate apartment or unit number in the signer's residence address shall not invalidate their signature pursuant to Section 105. A space at least one inch wide shall be left blank after each name for the use of the elections official in verifying the petition or paper.

(c) The part of a petition for the signatures, printed names, and residence addresses of the voters and for the blank spaces for verification purposes shall be numbered consecutively commencing with the number one and continuing through the number of signature spaces allotted to each section. The petition format shall be substantially in the following form:

(d) A county elections official who verifies signatures on an initiative, referendum, recall, nominating petition or paper, or any other petition or paper that is required to be signed by voters of a county, city, school district, or special district subject to petitioning may establish and require the use of a standardized petition form for distribution within and submission to the county.