[IBR-098-OM] - If Document level charge TAX category code (IBT-102) is 'E', Document level charge TAX rate (IBT-103) MUST not be present.
IBR-098-OMubl:Invoice/cac:AllowanceCharge[cbc:ChargeIndicator = 'true'] | cn:CreditNote/cac:AllowanceCharge[cbc:ChargeIndicator = 'true']not($cat='E') or not(cac:TaxCategory/cbc:Percent)