# ibr-099

Source: https://xmlvalid.com/rules/ibr-099

> Seller trader name (ibt-028) 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: `/ubl:Invoice | /cn:CreditNote`
- Test: `(count(cac:AccountingSupplierParty/cac:Party/cac:PartyName/cbc:Name) <= 1)`

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