# BR-CIUS-PT-51

Source: https://xmlvalid.com/rules/BR-CIUS-PT-51

> The Referenced purchase order line reference (BT-132) shall be filled.

- Level: error
- Rule sets: CIUS-PT rules (Portugal, UBL) 2.1.1
- Context: `cac:InvoiceLine | cac:CreditNoteLine`
- Test: `exists(cac:OrderLineReference) and not(cac:OrderLineReference/cbc:LineID)`

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