On Thu, Jun 06, 2019 at 01:49:19PM +0900, Jean-Christophe Helary wrote:
> I'm finding that Ctrl-[ is associated to Esc but I have nothing like this in my init file.
> 
> Hitting Ctrl-[ in C-h k also gives Esc.
> 
> Why is that ?

If you have a decent computer (and OS): go open a terminal and type
in "man ascii". You'll see two colums: those less than 64 (i.e.
characters with the second bit set to zero) and those 64 and beyond.

CTRL traditionally makes those "characters" normally non accessible
(because they aren't real characters) accessible by suppressing that
second bit: look to the right column.

Thus, CTRL-@ -> NULL, CTRL-A -> SOH, etc. (notably, CTRL-G is a bell,
CTRL-C is ETX (end of text), CTRL-D EOT (end of transmission). You
might recognize some conventions coming from that.

If you go down that two parallel columns, you'll see that ESC is
paired with CTRL-[

It's in your computer's reptile brain, not always visible, but
lurking :-)

Cheers
-- t