[ibr-036]-Charge (ibg-21) MUST have a charge amount (ibt-099).
ibr-036
cac:AllowanceCharge[cbc:ChargeIndicator = true()]
((exists(cbc:Amount) and not(ancestor::cac:InvoiceLine | ancestor::cac:CreditNoteLine))) or (ancestor::cac:InvoiceLine | ancestor::cac:CreditNoteLine)