# F-INV306

Source: https://xmlvalid.com/rules/F-INV306

> No more than one AllowanceCharge class may be present

- Level: error
- Rule sets: OIOUBL 2.1 Invoice rules (Denmark) 1.17.2
- Context: `doc:Invoice/cac:InvoiceLine/cac:BillingReference/cac:BillingReferenceLine`
- Test: `count(cac:AllowanceCharge) > 1`

Validate a document against these rules: https://xmlvalid.com/validate