# ibr-sr-28

Source: https://xmlvalid.com/rules/ibr-sr-28

> Mandate reference identifier (ibt-089) MUST occur maximum once

- Level: error
- Rule sets: PINT Billing rules 1.1.3, PINT Billing rules (as shipped with PINT AE) 1.0.4
- Context: `cac:PaymentMeans`
- Test: `(count(cac:PaymentMandate/cbc:ID) <= 1)`

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