Certificate of Origin requirements define issuance, alteration, validity and presentation rules for preferential tariff eligibility under the scheme. Procedural requirements govern issuance, form, distribution and admissibility of the Certificate of Origin under the Duty Free Tariff Preference Scheme. Issuing Authorities designated by the exporting Beneficiary government alone may issue acceptable certificates on prescribed A4 specimen with unique reference numbers and specified originals and copies. Alterations require authorised certification; certificates must be issued at exportation or within a short period thereafter, with limited retroactive issuance and certified true copy procedures for loss. Originals must be presented to Customs within validity; minor discrepancies do not ipso facto invalidate certificates, and Customs may verify or reject certificates with notification to issuing authorities.