bug#75398: 30.0.93; files.el documentation refers to "ITS-id" version control

[Eli Zaretskii <eliz@gnu.org>]

> From: Stefan Kangas <stefankangas@gmail.com>
> Date: Mon, 6 Jan 2025 09:46:02 +0000
> 
> Severity: wishlist
> 
> In files.el, I read this:
> 
>     ;;; Commentary:
> 
>     ;; Defines most of Emacs's file- and directory-handling functions,
>     ;; including basic file visiting, backup generation, link handling,
>     ;; ITS-id version control, load- and write-hook handling, and the like.
> 
> I understand that "version control" refers to backup files rather than
> VCS, but what is "ITS-id"?  I can't find any references to that in the
> manual, or by grepping, but since the text was written in 1993, is it
> possible that it refers to "Incompatible Time-Sharing System"...?

Yes, I think ITS was the system which introduced numbered backup
files.  Maybe someone else (Richard?) could confirm.

This commentary was added by Eric Raymond in March 1993.