Hello, total newbie here. Veteran computer guy but this is my first iThing. I have been playing around with some readers. iBooks, Adobe Reader, GoodReader, BlueFire, etc. What I seem to be finding is that books are accessible only to the app that was used to import them. Adobe Reader does not seem to have access to pdfs loaded by iBooks, etc. Is this correct? This seems crazy. i ought to be able to open a PDF with any pdf reader that I choose to use. More generally, I cannot find any evidence of a file system or any way to look at the files stored on the iPad. Obviously there is a file system in there somewhere but as a user how do I access it?