Greek Suppliers that send an invoice through the PEPPOL network to a greek buyer must use a correct TIN number as an electronic address according to PEPPOL Electronic Address Identifier scheme (SchemeID 9933)
cac:AccountingCustomerParty[$isGreekSenderandReceiver]/cac:Party/cbc:EndpointID
./@schemeID='9933' and u:TinVerification(.)