[ibr-tdd-26] – The cac:InvoicePeriod (BG-14) element MUST NOT contain elements other than cbc:StartDate (BT-073), cbc:EndDate (BT-074), and cbc:DescriptionCode (BT-008).
ibr-tdd-26/pxs:TaxData/pxs:ReportedTransaction/pxs:ReportedDocument/cac:InvoicePeriodcount(*[not(self::cbc:StartDate or self::cbc:EndDate or self::cbc:DescriptionCode)]) = 0