Re: Suggested experimental test

[Eli Zaretskii]

> Date: Mon, 22 Mar 2021 10:05:31 +0000
> From: Gregory Heytings <gregory@heytings.org>
> cc: ams@gnu.org, emacs-devel@gnu.org
> 
> 
> >> Even among the C-LETTER and M-LETTER keys, there are quite a few whose 
> >> meaning have changed during the last 40 years.  I know at least of: 
> >> C-h, C-l, M-g, M-j, M-n, M-o, M-p, M-r and M-s.  That's 9 keys out of 
> >> 52.
> >
> > Please describe those changes one by one.  At least for some of these 
> > keys I'm unaware of any changes in their bindings, so I'm curious what 
> > exactly is considered a "change" in this context.
> >
> 
> C-c: was initially exit-recursive-edit, and was changed to a prefix key 
> for modes in Emacs 16; exit-recursive-edit was then moved to C-M-c
> 
> C-h: was initially (and in other Emacsen) the same as C-b, and was (very 
> early in the development of GNU Emacs) changed into the help character
> 
> C-l: was 'recenter' up to and including Emacs 22, then became 
> 'recenter-top-bottom', which changes its semantics when is repeated
> 
> C-z: was initially (and in other Emacsen) a prefix character, was at some 
> point bound exit-recursive-edit, then became (in GNU Emacs 1.11) bound to 
> suspend-emacs
> 
> M-g: was initially bound to fill-region, was used for facemenu in Emacs 
> 19-21, and is used for goto-like commands since Emacs 22
> 
> M-j: was initially unused, became indent-new-comment-line in Emacs 1.7
> 
> M-n and M-p: were initially unused, became what they are now in Emacs 17
> 
> M-o: was unused before Emacs 22, was used for facemenu in Emacs 22-27
> 
> M-r: was initially unused, became 'move-to-window-line' in Emacs 16, then 
> became 'move-to-window-line-top-bottom', which changed its semantics when 
> it is repeated
> 
> M-s: was initially unused, became center-line for text-modes in Emacs 16, 
> and is used for search-like commands since Emacs 23

Thanks, this matches my recollection: only 3 keys (M-g, M-o, M-s) were
changed recently enough to count for this discussion.  The rest are
ancient history (more than 35 years ago), and C-l's change is very
much minor (it _adds_ to the previous user-visible behavior, but
doesn't change it).

So my summary would be different: since 35 years ago, only a handful
of these keys were ever changed.