Braille display buttons: touch configuration of upper buttons
I would like to know, on Braille displays, do the buttons in the top face have multiple configurations power button (eg., the button was pressed upwards, or downwards, sort of like with Max OS X mice, which have one button but can became clicked on one of the positions such add left, middle, and right). I was thinking, if the buttons could be pressed upwards our downwards then either:
More key combinations could be produced.
More comfortable key combinations could result, avoiding key combinations that were awkward to press.
Additionally, I would like to know where I can find a mapping off the upper button presses to actual characters. Where are the button presses / buttons, corresponding to the space, enter, and backspace characters located on such displays. What about the arrows to move forward, backwards, upwards, or downwards on such displays?
Thanks.