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