"Eventually I decided that I would like to have [ a Palm based PDA ] to use as a sort of eBook clone. I had used AportisDoc Mobile edition and noticed that (surprise!) it sucks a lot. Much of this apparent suckiness was due to it being the free version and being featured limited. I wasn't really looking forward to paying $30 for an ASCII viewer for the Palm. ... Anyway, all the other viewers used the "open" DOC format. Open only because somebody had reverse engineered it. Aportis wasn't very forthcoming. The problem is, DOC is not very good for storing book length texts. Well... it's not that good for storing much of anything. It uses, from the code I've seen, a "run length encoding" scheme to compress the text. If you know what RLE is, then you probably know that it's not the best thing to use to compress the written word. What it does have, however, is speed. But, I'm willing to put up with a 20 second decompression time when it means saving about 33% in space over DOC (more the larger the text is)."