[ALIGNED-IBRP-SR-12] - Seller VAT Identifier (IBT-031) must occur at most once.
ALIGNED-IBRP-SR-12ubl:Invoice | cn:CreditNotecount( cac:AccountingSupplierParty/cac:Party/cac:PartyTaxScheme [cac:TaxScheme/cbc:ID = 'VAT'] /cbc:CompanyID ) <= 1