bug#71822: Feature request: fullwidth to halfwidth

[Eli Zaretskii]

> From: Dan Jacobson <jidanni@jidanni.org>
> Date: Fri, 28 Jun 2024 17:06:55 +0800
> 
> M-l runs the command downcase-word.
> That's great. But here's a feature request:
> Have commands that can change wide to narrow,
> with the same ease as M-l.
> E.g., change ２０９Ｍ into 209M.
> and another command to do the opposite.
> OK, I guess they are called fullwidth and halfwidth.

When would such commands be useful?  These characters are deliberately
not the same, and not just different shapes of the same letters
(unlike upper-case and lower-case letters).