Greek suppliers that send an invoice through the PEPPOL network must use a correct TIN number as an electronic address according to PEPPOL Electronic Address Identifier scheme (schemeID 9933).
cac:AccountingSupplierParty/cac:Party[$accountingSupplierCountry='GR' or $accountingSupplierCountry='EL']/cbc:EndpointID./@schemeID='9933' and u:TinVerification(.)