Originally Posted by Nate the great
I don't see why you can't do it in other formats. Take HTML, for instance. A TOC is just a set of links to locations in a file. A nested TOC is one TOC with links to other TOCs, each of which have links to locations in the file.
The question here is about the Sony Reader. In the UI of the Sony Reader, you can have nested TOCs for PDF files. Jumping from page to page to access the right content, using an inline TOC is not a nested TOC. On the PRS-500/505 it's MUCH easier to access the TOC through the UI rather than with an inline TOC (faster with the 0-9 keys than with the joystick).