GR-R-004-2: When Supplier is Greek, the MARK Number must be a positive integer

The rule checks the MARK Number (cbc:ID) of an cac:AdditionalDocumentReference whose cbc:DocumentDescription is ##M.AR.K## when the supplier is Greek. In this UBL expression the supplier country is taken from the cac:AccountingSupplierParty postal address and must be GR; the $isGreekSender variable also accepts EL, but the applied condition explicitly requires GR. The value must match ^[1-9]([0-9]*), i.e. be a positive integer: the first character must be a digit 1–9 and any following characters digits, with no sign, decimal point, leading zeros, or surrounding whitespace.

Set the value of cac:AdditionalDocumentReference/cbc:ID for the ##M.AR.K## reference to a positive integer such as 123456. Remove any leading zeros, whitespace, negative sign, or decimal separator. If you see 0, 0123, -5, 1.5, or empty content, correct it to a plain positive integer.