Cal. Rev. & Tax. Code § 7403

(a)The certificate to be provided by a train operator consists of a statement that is signed under penalties of perjury by a person with authority to bind the buyer. A new certificate must be given if any information in the current certificate changes. The certificate may be included as part of any business records normally used to document a sale.

(b)An exemption certificate for motor vehicle fuel used in a motor vehicle fuel-powered train or for other off-highway use shall contain that information and be in the form as the board may prescribe.