Import a namespace
Namespace import is done by importing a nodeset2.xml file. Before you can import the file, an ApisSemantics module for your namespace must exist. See Create new namespace on how to create a module for your namespace. It is of crucial importance that the namespace Uri in the ApisSemantics module is exactly the same as the one in your nodeset2.xml file.
Follow the instructions in Import new/replace namespace from nodeset to complete the namespace import.