Proposal: "C-z <letter>" reserved for users

[S Boucher]

C-z is bound to a low frequency use function (suspend-frame)... and speaking 
for myself, I probably can count on one hand the number of times I've used it 
in the last 25years :-)

I would suggest:1) move suspend-frame to "C-c C-z" (that is still a quick 
shortcut)
2) reserve C-z <letter> for users
That still leaves a whole lot with C-z C-... C-z M-...