No idea either, devseev. The best I can do is this: When I first open the TOC of a book with bookmarks, notes, etc., the book icon at the end of the row is off (grayed). I tap the link icon (turn to gray), then tap the book icon and the link icon again. It seems a roundabout way to list the annotations, but I'm sure there's more to it and I just can't figure it out.
For a while, every time I'd read a book I'd tap the link icon: on, off, on, off. Nothing. Finally, I stopped when I remembered the old Steven Wright joke: "I have a switch in my house that does nothing. For the heck of it, every time I walk in the room, I flick it on and off a few times. Last week I got a call from a woman in Germany. She said, 'Knock it off.'"
(Just saw Boris' post. Yes, lock/unlock it is. And now, for Boris' next trick, he'll tell us what it does.

But no pressure....)