[IBR-099-OM] - If Document level charge TAX category code (IBT-102) is 'O', Document level charge TAX rate (IBT-103) MUST not be present.
IBR-099-OMubl:Invoice/cac:AllowanceCharge[cbc:ChargeIndicator = 'true'] | cn:CreditNote/cac:AllowanceCharge[cbc:ChargeIndicator = 'true']not($cat='O') or not(cac:TaxCategory/cbc:Percent)