I have done some looking at annotations for epubs and kepubs, but not PDF. The basics for epubs are in https://www.mobileread.com/forums/sho...d.php?t=199937
I thought text could be selected in some PDFs on the Glo, but my tests today show that it can't. The reader does let you create bookmarks by pressing the top right corner of the page. Notes can be added to these from the annotation list. A very quick test shows these are stored in an annot file just like for epubs. I have no idea if any other PDF reader will read these files and display the notes.