Control-Z key

I just purchased a Roland A800 Pro.  The setup was problem-free, and the key mapping was effortless and works perfectly. 
 
Unfortunately, being a real newbie with keyboard, I have no idea what the default key mappings consist of.  I am almost functional using the A800 as a controller for Sonar Platinum.  However, I cannot find a key on the controller that functions as 'Control-Z' which would allow me to 'undo'.  Does anyone know if the default Roland mapping includes a 'Control-Z' key, and, if yes, what key on the controller is mapped to that function.
Thanks a lot for the help.