In some client-server implementations the assignment of a permanent UUID may be done on the server. In these cases it is not practical for a newly created referenceable node to be given a UUID upon creation. Rather, it makes more sense for the UUID to be assigned upon save of that node. In such cases a “dummy UUID” may be assigned on creation of a new node while the real UUID assignment takes place later, upon save. Applications should not, therefore, rely on the UUID of a node before that node is saved for the first time.