I found this interesting tidbit of information. Here's a quote from a guy named David Wright (hmmm, what a coincidence, same initials).
"I've been bored, and trying to find out for someone how to discover the region of a given dvd. After loads of scouring, with my main pointer coming from the source for libmpdvdkit2, I've discovered that the region is set in byte 35 of a DVD's VIDEO_TS.IFO file. It's an 8-bit mask with set bits indicating forbidden regions."
I was trying to work this out for my self. This guy has save me lot's of hassles. Is there a resource available that gives the specs for files such as VIDEO_TS.IFO? That would be super dooper extra special handy!!