[ibr-148-ae]-The Seller VAT registration identifier (IBT-032) should be TIN (tax identification number) and must be 10 numeric digits and should be of the format 1XXXXXXXXXX.
ibr-148-ae
cac:AccountingSupplierParty/cac:Party/cac:PartyTaxScheme[cac:TaxScheme/normalize-space(upper-case(cbc:ID)) != 'VAT']/cbc:CompanyID
matches(., "^1[0-9]{9}$")