The site navigation utilizes arrow, enter, escape, and space bar key commands. Left and right arrows move across top level links and expand / close menus in sub levels. Up and Down arrows will open main level menus and toggle through sub tier links. Enter and space open menus and escape closes them as well. Tab will move on to the next part of the site rather than go through menu items.
Corney, R. H. (1987). Marital problems and treatment outcome in depressed women. A clinical trial of social work intervention. The British Journal of Psychiatry, 151(5), 652-659.