big list is here:

http://en.wikipedia.org/wiki/URI_scheme

not obvious how much to support...

in general, most things with a slash in them somewhere (and mailto: should work now.

  --Ethan McCutchen.....2013-04-03 17:11:43 +0000

This is just for external link syntax, right? I.e. [[irc://somenode]], not free links, right?

Then file:///filename.txt and irc://somenode.org are supposed to work?

I guess they do, cool.