OK, I have one more test that is unhappy with the quirks of namespaces, and don't know the implications of. it is essentially: "how does targetNamespace interact with default namespaces of things". If I have a CDL file which declares a target namespace, are all components installed into that namespace for reference by other things, including the components themselves? that is: does this document resolve the extension properly, or does it fail with an unknown element error: <?xml version="1.0"?> <cdl:cdl xmlns:cdl="http://www.gridforum.org/namespaces/2005/02/cddlm/CDL-1.0" targetNamespace="nap://velvet+underground/european+sun" xmlns:tns="nap://velvet+underground/european+sun"> <cdl:system> <Component /> <Extension cdl:extends="tns:Component"/> </cdl:system> </cdl:cdl> -steve ps. the nap: url schema was a relic of napster; each one searched for content under that name. I use it for unique names, but also to verify that whatever holds the URIs is not enforcing them to be resolvable URLs.