[ibr-tdd-28] – The cac:InvoiceDocumentReference element MUST NOT contain elements other than cbc:ID (BT-025) and cbc:IssueDate (BT-026).
ibr-tdd-28/pxs:TaxData/pxs:ReportedTransaction/pxs:ReportedDocument/cac:BillingReference/cac:InvoiceDocumentReferencecount(*[not(self::cbc:ID or self::cbc:IssueDate)]) = 0