# BR-CIUS-PT-35

Source: https://xmlvalid.com/rules/BR-CIUS-PT-35

> The Seller trading name (BT-28) shall be filled.

- Level: error
- Rule sets: CIUS-PT rules (Portugal, UBL) 2.1.1
- Context: `cac:AccountingSupplierParty`
- Test: `exists(cac:Party/cac:PartyName) and not(cac:Party/cac:PartyName/cbc:Name)`

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