# IS-R-008

Source: https://xmlvalid.com/rules/IS-R-008

> If seller is icelandic and invoice contains supporting description EINDAGI then the id form must be YYYY-MM-DD — Ef seljandi er íslenskur þá skal eindagi (BT-122, DocumentDescription = EINDAGI) vera á forminu YYYY-MM-DD.

- Level: error
- Rule sets: Peppol BIS Billing 3.0 rules 3.0.21
- Context: `ubl-creditnote:CreditNote[$SupplierCountry = 'IS'] | ubl-invoice:Invoice[$SupplierCountry = 'IS']`
- Test: `(exists(cac:AdditionalDocumentReference[cbc:DocumentDescription = 'EINDAGI']) and string-length(cac:AdditionalDocumentReference[cbc:DocumentDescription = 'EINDAGI']/cbc:ID) = 10 and (string(cac:AdditionalDocumentReference[cbc:DocumentDescription = 'EINDAGI']/cbc:ID) castable as xs:date)) or not(exists(cac:AdditionalDocumentReference[cbc:DocumentDescription = 'EINDAGI']))`

Validate a document against these rules: https://xmlvalid.com/validate