Bicycle Mechanics - Trek 7300 Fork/Stem question

I am familiar with the threadless fork/headset/stem combination found on my other bikes, but I am confused when trying to learn about my newer Trek 7300. Looks like a quill stem, but appears to also clamp on? Specs indicate the headset would be threadless, but if so I, don't understand what keeps it all together with neither a lock nut nor a compression nut. I wish I could give detailed information about the parts in question as per the "new posters" sticky thread, but lack of available info is the problem. Fork is the Bontrager SPA integrated suspension one, headset is "aheadset slimstak" and zero information on the adjustable rise stem.

Thanks in advance if anyone can shed some light on what I'm missing!

Pictures?

http://user00.freeshell.org/7300-2.jpg

http://user00.freeshell.org/7300.jpg


I'm assuming that's just a spacer seen immediately below the stem, and not a lock nut, so this is why I'm confused as to what combination of threaded and/or unthreaded components are being used here.

This looks like a standard clamp-on threadless stem but closed on top. I assume there is a star nut inside the fork steerer. I further assume that the bolt head seen at the top of the stem is long enough to reach the starnut and is used to adjust the headset just like the bolt through the top cap of a more conventional set-up.

^^^ +1 ^^^ Just has the cap integrated into the stem.

Thank you both for the help, it makes a LOT more sense to me now that I'm not wondering what's up with the stem. :D