I spent some time researching this issue in the context of some other projects I've been following or involved in (OWS context Standards Working Group, energy industry ISO19115 metadata profile, and USGS CGI Web Application Integration Framework group). I would like to see this considered in a larger context to come up with a solution that can be used in these various contexts, because it's essentially the same problem.
Here' s the gist of the proposal for link attributes outlined in the attached doc:
href -- the link URL
type -- MIME type of response. Specifies encoding and optionally the native software application environment. We're sort of stuck with this because of existing usage. One big question is how much of serviceType, puprpose, and outputScheme it makes sense to conflate in the MIME type. I favor keeping the MIME type limited to low-level file formatting--to answer the question 'what software can read this file in a useful way' Understanding the content and intention of a document or the interface to a service should be specified by separate properties.
Now that we have a better grasp of the IT and informatics challenges of a distributed and interoperable information network, we can think more again about its adoption - how to make it work and useful on the ground. Following was our rough chain of thought on metadata: