Clicking the "+" does nothing more than allow referencing another directory where Poser content can be found. There is nothing unique about the file structure and nothing is changed in the Poser 4 Runtime directory. This basically lets Poser 5 look into and use the content in Poser 4 as if it was installed for Poser 5. Page 124 isn't the best spot in the world to put this tip in the manual (and it's on 126 in mine) and it actually comes kind of late to learn it because I mostly reinstalled everything and have duplicate stuff in 4 and 5. Hopefully somebody at CL will consider putting this kind of info in the installation section, if the manual is upgraded or a new release goes out, because there aren't many people who will closely enough scrutinize a whole manual before using the program. I'll flip through new features and stuff when I upgrade a program and thumb through a manual to see if anything interesting catches my eye. When there's time, I'll read a manual cover to cover, but not when I first open the package. Even if a person read the manual thoroughly, it's not likely that person would have realized what that section meant. It doesn't quite come out and say that this is a way to read Poser 4 content. The manual talks about this feature as a means to store content in different drives and directories. Unless somebody has an immediate need to put things in different directories or drives, it's one of those features that's easy to forget about. It's obvious to me after reading the tip, but it would have saved me a lot of time had the manual mentioned this goodie up front.