# F-REM090

Source: https://xmlvalid.com/rules/F-REM090

> AdditionalDocumentReference class must be excluded

- Level: error
- Rule sets: OIOUBL 2.1 Reminder rules (Denmark) 1.17.2
- Context: `doc:Reminder/cac:ReminderLine/cac:BillingReference`
- Test: `count(cac:AdditionalDocumentReference) = 0`

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