Vendors who are not closely familiar with OPC UA sometimes create their product specific nodes in the wrong address space like e.g. namespace 0. This is a problem for interoperability since some products have pre-knowledge of namespace 0 nodes and therefore treat them differently then nodes in other namespaces.

This can be checked by checking if all nodes in namespace 0 are known to the CTT. If we find any node which cannot be matched, then printing errors for those nodes. Of course this will require to check the namespace object for the namespace 0 first and the check can only be done when the namespace version in the product under test is older or similar to the one known in the CTT. If the namespace is newer all additional nodes can only be indicated either as warning or information, since they may be legitimate nodes from the newer namespace.