"Customs Number" refers to the number given to a Customs Declaration Form by the Customs upon their accepting a declaration. An Import Declaration Form and an Export Declaration Form shall be separately numbered. The number of a Customs Declaration Form consists of 18 digits, therein the 1st-4th digits refer to the number of the Customs accepting a declaration, the 5th-8th digits refer to the calendar year of a Customs-accepted declaration, the 9th digit indicates the import/export mark ("1" for import, "0" for export), and the remaining 9 digits refer to a sequence number.