[IBR-065-OM] - When Invoice currency code (IBT-005) is not equal to 'OMR' and Tax accounting currency [IBT-006] is 'OMR', then the value in Invoice total VAT amount in tax accounting currency [IBT-111] MUST be provided and must be Exchange rate (BTOM-003) multiplied by Invoice total tax amount (IBT-110).
IBR-065-OMubl:Invoice | cn:CreditNotenot($invoiceCurrency != 'OMR' and $taxCurrency = 'OMR') or ( $exchangeRate castable as xs:decimal and u:slack( xs:decimal((cac:TaxTotal[cbc:TaxAmount/@currencyID = $taxCurrency]/cbc:TaxAmount)[1]), xs:decimal($exchangeRate * (cac:TaxTotal[cbc:TaxAmount/@currencyID = $invoiceCurrency]/cbc:TaxAmount)[1]), 0.02 ) )