For an example of the problems NOT doing this might cause, see eg
http://lists.gnu.org/archive/html/bug-gnu-emacs/2006-07/msg00000.html
Eg after:
(global-set-key (kbd "C-u") ctl-x-map)
(global-set-key (kbd "C-x") 'universal-argument)
just loading dired-x.el or term.el would give an error.
* lisp/dired-x.el (dired-bind-jump): Use ctl-x-map and ctl-x-4-map.
* lisp/term.el (term-raw-escape-map): Use Control-X-prefix.
* lisp/vc/vc-hooks.el (vc-prefix-map): Use ctl-x-map.
It hasn't worked in a VC sense since 2008-05-02T07:12:59Z!esr@snark.thyrsus.com, though this was
not documented at the time (grr).
* lisp/vc/vc-hooks.el (vc-toggle-read-only): Make it an obsolete alias
for toggle-read-only. Note that this hasn't called vc-next-action
since 2008-05-02, though it wasn't documented at the time.
* lisp/files.el (toggle-read-only): Remove obsolete comment about
version control.
* doc/emacs/buffers.texi (Misc Buffer): Don't mention vc-toggle-read-only.
* lisp/cedet/ede.el (ede-maybe-checkout): Function deleted;
vc-toggle-read-only does not do version control now.
* lisp/cedet/ede/project-am.el (project-remove-file, project-add-file)
(project-new-target): Don't call ede-maybe-checkout.
* lisp/cedet/ede/util.el (ede-make-buffer-writable): Don't use
vc-toggle-read-only.
* lisp/vc/ediff-init.el (ediff-toggle-read-only-function): Use
toggle-read-only.
lisp/vc/vc-hooks.el (vc-default-mode-line-string): Doc fix.
doc/emacs/maintaining.texi (VC Mode Line): Mention all the possible VC
status indicator characters.
