In implementing cdl:types, I have run into a few questions: To define types, you need to do what the full-example-1.cdl document taken from the CDL spec does. <cdl:types> <xsd:schema> ...... </xsd:schema> </cdl:types> But, if we allow any random XML from any namespace in there as the CDL schema does, then I have to go sorting around dumping what is uninteresting, and finding if there is really any schema to be had. I know it is valid, it is just a lot of extra work. There is also a problem with defining multiple schemas within the cdl:types element. In order to support multiple schemas, the cdl:cdl/@targetNamespace attribute has to be multivalued or multiply defined. Is this the expectation? It is really easy to change <cdl:types>? <cdl:documentation .../>? <-- schema definition -->* <-- extensibility element -->* </cdl:types> to <cdl:types>? <-- schema definition --> </cdl:types> In this way, there is one local schema and one targetNamespace attribute. Also, what is the "extensibility element"? Stuart