[IBR-005-OM] - Currency exchange rate (BTOM-003) should contain the values till maximum of 7 decimal places when the VAT accounting currency (IBT-006) is set to OMR and the invoice currency code (IBT-005) differs from OMR.
IBR-005-OMubl:Invoice | cn:CreditNotenot($taxCurrency='OMR' and $invoiceCurrency!='OMR') or (exists($exchangeRate) and $exchangeRate = round($exchangeRate * 10000000) div 10000000)