# BR-CIUS-PT-33

Source: https://xmlvalid.com/rules/BR-CIUS-PT-33

> The Project reference (BT-11) shall be filled.

- Level: error
- Rule sets: CIUS-PT rules (Portugal, UBL) 2.1.1
- Context: `cac:ProjectReference`
- Test: `exists(cbc:ID)`

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