Chessbase opening encylopedia

I was wondering if anybody used Chessbase’s Opening Encyclopedia. (I don’t have it).

I was curious as to what an Opening Survey was, and what a “Special Theory Database” was.

I understand the Opening Survey and Special Theory stuff comes from the Chessbase Magazine. Are all the special theory databases contained in the larger database, and not seperate databases? (It would be rather burdensome to have to open 506 different “special theory” databases.)

Anyway, if anybody has used that, also some general comments on the database as a whole would be welcome.
-I looked at a couple online reviews of the opening encyclopedia, but both assumed the reader was familiar with both the opening surveys and the special theory databases.

I mean, and opening survey should be more than just a list of games with X and Y moves, since thats one of the most basic elements of any chess database, being able to spit out games with a particular position.