For Danish Suppliers if the PaymentID is prefixed with 04# or 15# the 16 digits instruction Id must be added to the PaymentID eg. "04#1234567890123456" when Payment means equals 50 (Giro)
ubl-invoice:Invoice[$DKSupplierCountry = 'DK' and $DKCustomerCountry = 'DK']/cac:PaymentMeansnot((cbc:PaymentMeansCode = '50')       and ((substring(cbc:PaymentID, 1, 3) = '04#')          or (substring(cbc:PaymentID, 1, 3)  = '15#'))       and not(string-length(cbc:PaymentID) = 19)       )