In mozilla we currently don't allow relative URIs in the href at all. If
the uri is relative it is ignored. This is per HTML4, and I think it
would be ok for HTML5 to say the same.
Alternatively it could say that it should be relative to the URI used to
retrieve the <base> element. In most cases the URI of the document.
Note that the current text isn't implementable since it says that
relative uris in <base> should be resolved against the base uri
document, but the <base> element modifies that base uri so there is a
circular dependency.
/ Jonas
