Editing the Book Template I'd like to edit the way the Book navigation is structured.
I'd like to be able to edit the html output of the book.

I was looking for a way to do this with the book template but had no luck. Looking at book-navigation.tpl.php I did see that $tree contained the children of the current node. However it used like this

&lt;?print $tree; ?&gt;


I don't see a way to alter the html of how the tree is output.
The theme hook you'll want is menu_link__book_toc_123, where 123is the node ID of your book's outline node.
For the wrapping markup, use menu_tree__book_toc_123.

You can also find the ID by inspecting the navigation list: