Determine which tracks have DRM in iTunes

This might be a silly question, but I've upgraded my iTunes-bought music on a number of occasions as non-DRM tracks became available. iTMS seems to know easily enough if there are tracks available for upgrade, so I assume there is some kind of flag that determines which are DRM-ridden and which are not. Is there any way for me to make that determination?

I cannot see a way in iTunes to do this.

But if you do a Spotlight search for AAC (protected) the DRM tracks come up

I'm not sitting in front of my Mac at the moment, but there's a tag in iTunes you can use in the columns view that tells you what "type" the song is. With iTunes purchases... it'll either say something like "Protected AAC" or "Purchased AAC". The "Purchased" ones are DRM-free. Just sort by that column, or make a smart playlist.

lifeisabeach is correct. Have it show the KIND column and it will show you if it's Protected AAC there. I have always had it display the KIND column for that reason.

Perfect, thanks guys. That's exactly what I needed.