# CII-SR-497

Source: https://xmlvalid.com/rules/CII-SR-497

> Mandate reference identifier (BT-89) shall occur maximum once.

- Level: error
- Rule sets: EN 16931 rules (CII) 1.3.17
- Context: `/rsm:CrossIndustryInvoice/rsm:SupplyChainTradeTransaction/ram:ApplicableHeaderTradeSettlement`
- Test: `count(ram:SpecifiedTradePaymentTerms/ram:DirectDebitMandateID) <= 1`

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