# F-CRN172

Source: https://xmlvalid.com/rules/F-CRN172

> DebitNoteDocumentReference class must be excluded

- Level: error
- Rule sets: OIOUBL 2.1 Credit Note rules (Denmark) 1.17.2
- Context: `doc:CreditNote/cac:CreditNoteLine/cac:BillingReference`
- Test: `count(cac:DebitNoteDocumentReference) = 0`

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