In the UBook format the table of contents is automatically compiled. Authors and publishers only add special markers throughout the manuscript where they want the reader to jump to e.g. above a chapter heading.
The text used with the marker is itself used to create the content for the table of contents. It looks like this:
To create a contents page (usually right after the title page) just add one tag where you want the table of contents to be displayed ($TOC); the software does the rest.
See below for links to information about the simple tags used.