If seller is icelandic and invoice contains supporting description EINDAGI the id date must be same or later than due date — Ef seljandi er íslenskur þá skal eindagi (BT-122, DocumentDescription = EINDAGI) skal vera sami eða síðar en gjalddagi (BT-9) ef eindagi er til staðar.
ubl-creditnote:CreditNote[$SupplierCountry = 'IS'] | ubl-invoice:Invoice[$SupplierCountry = 'IS'](exists(cac:AdditionalDocumentReference[cbc:DocumentDescription = 'EINDAGI']) and (cbc:DueDate) <= (cac:AdditionalDocumentReference[cbc:DocumentDescription = 'EINDAGI']/cbc:ID)) or not(exists(cac:AdditionalDocumentReference[cbc:DocumentDescription = 'EINDAGI']))