Use this button to open the Locations window, where you can select different modes - Bookmarks, Outlines, and Annotations
There are 2 types of Bookmarks - the ones created by you, and the ones embedded into a PDF file (also known as Table of Contents, Sidebar Reference or
Embedded bookmarks (Outlines) structured in a tree hierarchy. To save precious screen space, outlines only for the current level are shown. To see outlines of the next level,
press a blue arrow to the right of the outline of interest.
Select a bookmark or an entry in annotations summary list to instantly go to its location.