Again, a weird combo? I see on Wikipedia that there are other ones bigger than the latter four (the former four of course are the ones first seen by Galileo). First letter acronyms at work? Come on, there must be something!
UPDATE - Get yourself over to DocArzt stat for a video from inside the booth!!! The info is not great, I think the tests themselves are merely random questions, though they will probably from this indicate personality and what job you should do for DHARMA.
Click on Picture to Embiggen