Message

Element 'cbc:ID' MUST contain value 'VAT'.

Context
/ubl:Order/cac:OrderLine/cac:LineItem/cac:Item/cac:ClassifiedTaxCategory/cac:TaxScheme/cbc:ID
Test
normalize-space(text()) = 'VAT'
Usage
/ ubl:Order / cac:OrderLine / cac:LineItem / cac:Item / cac:ClassifiedTaxCategory / cac:TaxScheme / cbc:ID