Guys, I think
Steve Jordan means that every edition of a book you buy from his site has some sort of mark that if you share the book over the Internet it can be tracked down to the initial owner the copy

(something like...when you buy lrf file, it has an embeded numner 017, next lrf has a number 018 etc., if you know where to look for the number when you open the file you can find it)
I agree with that type of DRM.
P.S. I could be totally wrong in assuming what type of DRM he is taling about