Each Document level allowance (ibg-20) shall contain a Document level allowance reason (ibt-097) or a Document level allowance reason code (ibt-098), or both.
/ubl:Invoice/cac:AllowanceCharge[cbc:ChargeIndicator = false()] | /cn:CreditNote/cac:AllowanceCharge[cbc:ChargeIndicator = false()]exists(cbc:AllowanceChargeReason) or exists(cbc:AllowanceChargeReasonCode)