Message

If the tax currency code is different from the document currency code, each tax subtotal has to include the tax amount in both currencies

Context
/ubl:CreditNote/cac:TaxTotal/cac:TaxSubtotal
Test
not(/ubl:CreditNote/cbc:TaxCurrencyCode) or (cbc:TaxAmount and cbc:TransactionCurrencyTaxAmount)
Usage
/ ubl:CreditNote / cac:TaxTotal / cac:TaxSubtotal / cbc:TransactionCurrencyTaxAmount