California Code, Penal Code - PEN § 27220

(a) Within seven calendar days of the commencement of a gun show or event, but not later than noon on Friday for a show or event held on a weekend, the producer shall submit a list of all prospective vendors and designated firearms transfer agents who are licensed firearms dealers or ammunition vendors to the Department of Justice for the purpose of determining whether these prospective vendors and designated firearms transfer agents possess valid licenses and are thus eligible to participate as licensed dealers or ammunition vendors at the show or event.

(b) The department shall examine its records and if it determines that a dealer's or vendor's license is not valid, it shall notify the show or event producer of that fact before the show or event commences.