`self-insert-uses-region-functions'?

[Drew Adams <drew.adams@oracle.com>]

What can anyone tell me about this symbol, whose value is presumably
a function or a list of functions.  The only use I see of it in the
Emacs code is as a `delete-selection' TYPE value.  For example:

(put 'self-insert-command 'delete-selection
     (lambda ()
       (not (run-hook-with-args-until-success
             'self-insert-uses-region-functions))))

(Similarly, for some other functions besides `self-insert-command'.)

That's fine (hook variables need not be defined or documented), but it
seems like this hook, with such an evocative name ;-), might have some
intended meaning beyond use by `delete-selection-mode'.  (Else why
"use-region" instead of something about delete-selection?)

This seems to have been introduced without any real use of it, so far.
So I'm curious what the intention is.