Message

[UBL-SR-18]-Buyer VAT identifier shall occur maximum once

Context
/ubl:Invoice | /cn:CreditNote
Test
(count(cac:AccountingCustomerParty/cac:Party/cac:PartyTaxScheme[cac:TaxScheme/upper-case(cbc:ID)='VAT']/cbc:CompanyID) <= 1)