Certificate of Origin safeguards provisional entry pending verification, with possible denial if exporter refuses verification. Export consignments with an authentic Certificate of Origin are not to be detained; on reasonable doubt the importing customs may seek clarification from the certifying authority within thirty days and admit the consignment on a provisional basis against a bond pending final assessment. If clarification remains inconclusive, the importing Party may, after informing the exporting Party and with the importer's knowledge and exporter/manufacturer consent, conduct an on site verification; absence of consent within forty five days permits disallowance of the tariff preference for that certificate.