# F-INV331

Source: https://xmlvalid.com/rules/F-INV331

> Only use Delivery.RequestedDeliveryPeriod if not specified on header level (Invoice.Delivery)

- Level: error
- Rule sets: OIOUBL 2.1 Invoice rules (Denmark) 1.17.2
- Context: `doc:Invoice/cac:InvoiceLine`
- Test: `cac:Delivery/cac:RequestedDeliveryPeriod and count(../cac:Delivery/cac:RequestedDeliveryPeriod)`

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