# BR-CIUS-PT-24

Source: https://xmlvalid.com/rules/BR-CIUS-PT-24

> The Purchase order reference (BT-13) or the Sales order reference (BT-14) shall be filled, or both.

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

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