Section 173
SEC. 173. Each entry and all papers pertaining thereto, including invoices and bills of lading, shall be designated by a serial number. Every invoice, as soon as entered, shall be stamped with the date of entry and certified by the signature of the collector or his deputy or other customs officer duly designated, and the officer whose duty it is shall compare the classification made by the importer with the description given in the invoice, and shall see that the merchandise is classified at the rates provided by law.