California Code, Penal Code - PEN § 27205

(a) Before commencement of a gun show or event, the producer thereof shall, upon written request from a law enforcement agency with jurisdiction over the facility, make available to that agency, within 48 hours or a later time specified by the agency, a complete and accurate list of all persons, entities, and organizations that have leased or rented, or are known to the producer to intend to lease or rent, any table, display space, or area at the gun show or event for the purpose of selling, leasing, or transferring firearms, or processing the sale or transfer of ammunition.

(b) The producer shall thereafter, upon written request, for every day the gun show or event operates, within 24 hours or a later time specified by the requesting law enforcement agency, make available to that agency an accurate, complete, and current list of the persons, entities, and organizations that have leased or rented, or are known to the producer to intend to lease or rent, any table, display space, or area at the gun show or event for the purpose of selling, leasing, or transferring firearms, or processing the sale or transfer of ammunition.

(c) Subdivisions (a) and (b) apply to any person, entity, or organization, regardless of whether that person, entity, or organization participates in the entire gun show or event, or only a portion thereof.

(d) The information that may be requested by the law enforcement agency with jurisdiction over the facility, and that shall be provided by the producer upon request, includes, but is not limited to, the following information relative to a vendor who offers for sale any firearms manufactured after December 31, 1898, or any ammunition: