Cal. Pub. Util. Code § 29280

When a bond, note, interest coupon, or other evidence of indebtedness payable from funds in the custody of the chief financial officer of the district is presented to the chief financial officer for payment and is not paid for want of funds, the chief financial officer shall endorse upon it “Not paid for want of funds,” the date of presentation, and a serial number indicating the order of presentation, and shall sign or stamp their name on it.