For Danish Suppliers it is mandatory to use schemeID when PartyIdentification/ID is used for AccountingCustomerParty or AccountingSupplierParty
ubl-creditnote:CreditNote[$DKSupplierCountry = 'DK' and $DKCustomerCountry = 'DK']/cac:AccountingSupplierParty/cac:Party/cac:PartyIdentification | ubl-creditnote:CreditNote[$DKSupplierCountry = 'DK' and $DKCustomerCountry = 'DK']/cac:AccountingCustomerParty/cac:Party/cac:PartyIdentification | ubl-invoice:Invoice[$DKSupplierCountry = 'DK' and $DKCustomerCountry = 'DK']/cac:AccountingSupplierParty/cac:Party/cac:PartyIdentification | ubl-invoice:Invoice[$DKSupplierCountry = 'DK' and $DKCustomerCountry = 'DK']/cac:AccountingCustomerParty/cac:Party/cac:PartyIdentification
not((boolean(cbc:ID)) and (normalize-space(cbc:ID/@schemeID) = '') )