California Code, Government Code - GOV § 56704

(a) Each person signing a petition shall, at the time he or she signs the petition, affix after his or her signature the date upon which he or she signs the petition.

(b) If a petition is signed by registered voters, each person signing the petition shall, in addition to his or her signature, affix the date upon which he or she signs the petition and indicate on the petition his or her place of residence, giving street and number or other designation sufficient to enable the place of residence to be readily ascertained.

(c) If a petition is signed by owners of land, each person signing the petition shall, in addition to the signature and the date on which he or she signs the petition, include a written description sufficient to identify the location of the land owned by each person signing the petition.