Procedure for defacement of Certificate of Origin at TSK when preferential duty is claimed; importer may deface COO before registration. Where a preferential rate of duty is claimed based on a valid Certificate of Origin and the Bill of Entry is facilitated by RMS for OOC, the importer or Customs Broker may get the COO defaced by the designated TSK prior to registration of goods to streamline assessment and clearance; implementation difficulties should be reported to the issuing authority.