A wholesale dealer in liquors may continue to use records of receipt and disposition in a format previously prescribed or approved. Those records must show the information required by paragraph (a) of Sec. 31.155 or paragraph (a) of Sec. 31.156, as applicable. The records must be preprinted with the name and address of the wholesale dealer. Each sheet or page must bear a preprinted serial number, or page serial numbers may be affixed in unbroken sequence during the preparation or processing of the records. A serial number must not be duplicated within a period of 6 months. (26 U.S.C. 5121)