[BR-41]-Each Invoice line allowance (BG-27) shall have an Invoice line allowance amount (BT-136).
BR-41
//cac:InvoiceLine/cac:AllowanceCharge[cbc:ChargeIndicator = false()] | //cac:CreditNoteLine/cac:AllowanceCharge[cbc:ChargeIndicator = false()]
exists(cbc:Amount)