<link rel="alternate" media="handheld" href="http://m.example.com" />
I've seen this, and variations of this, used a lot to direct (I assume) search engines to the appropriate versions of a web page. But I have never been able to find an authoritative list of media types anywhere. Does one exist? Are there media types for tables for example? Not quite mobile, not quite standard web? Are there media types for ancient/obsolete browsers? It's a hard thing to search for, because all of the words involved are so generic. "link alternate media tag"