"translated from" keystrokes

[J. David Boyd]

When I C-h k C-S-w, I get this message:

C-w (translated from C-S-w) runs the command kill-region

I looked through the emacs docs, and it says that key translations are
explained in the elisp manual, and I've read through that, but
probably not enough, as I still don't know how to break this
translation, so I can assign a function to C-S-w.

Now, I can put the following text into my scratch buffer
(global-set-key [control shift w] 'emacs-uptime)
and evaluate it with C-x C-e, and the mode line says emacs-uptime.

Still, C-h k C-S-w reports kill-region.  Actually, C-h k shows that it
is reporting on C-w, so the key translation must be happening at a
very low level.

Any clues, please?

Dave