A Server managing Nodes needs to uniquely identify them in its AddressSpace. As a NodeId consists of a Namespace(Index) and an Identifier part, both parts can be used to guarantee uniqueness. Selecting the best approach depends on implementation details of the server. However, as a general guideline managing a namespace is the more expensive operation than managing another identifier in an existing namespace. Therefore, Server implementations should avoid to create many (hundreds of) namespaces and rather manage many Nodes in one namespace.

In the case of a Client creating Nodes (and thereby NodeIds) in a Server, it is recommended that the Client does not define the NodeId, but instead allows the Server to define a NodeId and return it to the Client.