The following navigation utilizes arrow, enter, escape, and space bar key commands. Left and right arrows move through
main tier links and expand / close menus in sub tiers. When focused on Expand / Collapse button, use Up, Down and Enter buttons to open sub navigation. Up and Down arrows will sort
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.