The Ubuntu SDK appears to be only for creating Ubuntu Apps. What exactly is an "Ubuntu App"? The website is very detailed, but I can't see any description of what is meant by an Ubuntu App.
I understand that these apps can run on either the desktop or an Ubuntu phone, but which desktop? Is it specifically Unity, or will these apps be usable on Xubuntu, Kubuntu, Ubuntu MATE, or even Linux Mint?
Or does this depend on whether or not I use any Unity specific hooks?
Edit: the referenced website has been updated since I asked this, so the question is not really relevant any more.