# GR-R-004-2

Source: https://xmlvalid.com/rules/GR-R-004-2

> When Supplier is Greek, the MARK Number must be a positive integer

- Level: error
- Rule sets: Peppol BIS Billing 3.0 rules 3.0.21
- Context: `cac:AdditionalDocumentReference[$isGreekSender and ( /*/cac:AccountingSupplierParty/cac:Party/cac:PostalAddress/cac:Country/cbc:IdentificationCode = 'GR') and cbc:DocumentDescription = '##M.AR.K##']/cbc:ID`
- Test: `matches(.,'^[1-9]([0-9]*)')`

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