Each Invoice line charge shall have an Invoice line charge reason or an invoice line allowance reason code.
//cac:InvoiceLine/cac:AllowanceCharge[cbc:ChargeIndicator = true()] | //cac:CreditNoteLine/cac:AllowanceCharge[cbc:ChargeIndicator = true()]exists(cbc:AllowanceChargeReason) or exists(cbc:AllowanceChargeReasonCode)