Certificate of origin rules require prescribed format, unique serials, copies, strict alteration controls and retrospective and replacement procedures. Certificates of origin under the Duty Free Tariff Preference Scheme must be issued by the authorised issuing authority in the Annexure C format on ISO A4 paper, in English, and bear a unique serial number and the applicable local value added content. Each certificate comprises one original and three copies with defined distribution and retention by exporter, importer and issuing authority. Alterations are tightly controlled. Certificates must be issued at exportation or within seven working days, with limited retrospective issuance and certified true copy procedures for loss or destruction.