Cal. Gov. Code § 9516
Except as otherwise provided in this section, every bill which has passed both houses of the Legislature, and has not been returned by the Governor within 12 days, thereby becoming a law, is authenticated by the Governor causing the fact to be certified thereon by the Secretary of State in the following form: "This bill having remained with the Governor 12 days, and the Legislature being in session, it has become a law this ____ day of ____, ____." The certificate shall be signed by the Secretary of State and deposited with the laws in his office.
Upon the receipt of such a bill and certificate, the Secretary of State shall assign a chapter number to the bill in the manner provided in Section 9510.
Every bill which has been passed by the Legislature before September 1 of the second calendar year of the biennium of the legislative session, which was in the possession of the Governor on or after September 1, and which has not been returned by the Governor on or before September 30 of that year, thereby becoming a law, is authenticated by the Governor causing the fact to be certified thereon by the Secretary of State in the following form: "This bill having been passed by the Legislature before September 1 of the second calendar year of the biennium of the legislative session, having been in the possession of the Governor on or after September 1 of such year, and having remained with the Governor through September 30 of such year, it has become a law this ____ day of ____." The certificate shall be signed by the Secretary of State and deposited with the laws in his office.
Upon the receipt of such a bill and certificate, the Secretary of State shall assign a chapter number to the bill in the manner provided in Section 9510.
Ca. Gov. Code § 9516