Emacs in LispWorks

I'd like to bind the Undo command to keypad "-".

1. What is the key name for keypad "-"?  Although "Kp-Enter" is valid, 
"Kp-Subtract" doesn't work, for example.

2. In the Editor User Guide, 6.1, values for :mode such as "Echo Area" are 
mentioned.  I also see that Edi Weitz uses "Execute" and "Lisp". Are these 
values documented further in the manuals?

Mitch