Originally Posted by Skydog
Actually, the statement in bold is not correct. As posted here previously, I have always converted my mobi books via Calibre with a [PDOC] tag and they always appear on the BOOKS bookshelf when side-loaded.
That's because you use a Calibre Profile that doesn't use the tag system. I believe that Calibre only uses the tag system on the Kindle Profile (Not sure about Kindle Fire profile). So it's really isn't adding the pdoc tag to any of your books because you are using the Kindle DX profile.
I use the Hanlin 5 profile on Calibre and it never adds tags to it either.