The bookmark tree is accessible via the View tab in the XF Designer 2011 ribbon. The Bookmarks checkbox toggles the visibility of the tree:

 

 

The bookmark tree displays all the bookmarks in the document and allows adding new bookmarks, as well as removing or editing existing ones.

Bookmarks can point to any XSL-FO object with its id attribute set to a particular value. The bookmark tree will show next to each bookmark the id of the object it's pointing to.

This example shows 4 bookmarks in the bookmark tree:

 

 

The bookmarks will show up in any output format that supports it, like PDF or EPUB.

 

The buttons on top of the bookmark tree allow managing your bookmarks via the Bookmark dialog.