In an Invoice line (ibg-25) where the Tax category code (ibt-151) is "O (Outside of scope of tax)" shall not contain an Invoiced item tax rate (ibt-152).
cac:InvoiceLine/cac:Item/cac:ClassifiedTaxCategory[normalize-space(cbc:ID) = 'O'][cac:TaxScheme/normalize-space(upper-case(cbc:ID))='VAT'] | cac:CreditNoteLine/cac:Item/cac:ClassifiedTaxCategory[normalize-space(cbc:ID) = 'O'][cac:TaxScheme/normalize-space(upper-case(cbc:ID))='VAT'](not(cbc:Percent))