Nope, not available in 9.1, which is why I was hoping you were on 10 or 10.1.
You will not find prt, asm, or drw extensions in the cache. They are hashed names. The extensions will simply tell you if it is a local only file (never been checked in), or a server file.
If you search the forums there is a tool that will give you the details on the cache files, but I wouldn't recommend using that as part of your daily process. Short term, until you upgrade to a later version, I would say do a check in if you think you want to roll backwards.