Certificate of origin requirements: invoice-linked sworn declarations must accompany third party invoicing or tariff preferences are denied. Rule 16 requires the final producer or exporter to present the first commercial invoice and a sworn declaration certifying that goods meet origin criteria, limits value addition to that performed within a Signatory Party, and mandates that the Origin Certificate record third-operator invoice details; if those details cannot be recorded, the Commercial Invoice attached to the Importation Request must include a sworn declaration linking it to the Origin Certificate with the certificate number and date, failure of which permits customs to reject the certificate and deny tariff preferences.