rddl:nature for WADL and OpenSearch?

I am glad to see RDDL being used by W3C and OASIS for namespace documents.
http://del.icio.us/mitrepauld/rddl+xmlns

What if one of these namespace documents (or any RDDL document, 
perhaps not associated with a namespace) wanted to point to a WADL or 
OpenSearch description?

What rddl:nature or xlink:role should be used?

<q cite="http://www.rddl.org/natures/">
When a referenced resource is XML and its nature can be inferred from 
the namespace URI of the root element, this namespace URI is the 
nature of the referenced resource.
</q>

So, WADL would use

rddl:nature="http://research.sun.com/wadl"

OpenSearch 1.1 would use

rddl:nature="http://a9.com/-/spec/opensearch/1.1/"

http://www.opensearch.org/Specifications/OpenSearch/1.1

Comments?

Paul