RE: C-x a C-x C-h

[Drew Adams]

> When I hit `C-x a C-x' in the latest Emacs, it awaits further input,
> as if it was a prefix key sequence. However, `C-x a C-x C-h' reveals
> that there are no commands bound to anything beginning with that
> prefix. Why?

Good question. I wonder too. Same thing in Emacs 22, 21, and 20.
And C-x C-x C-x C-x C-x ... just keeps on keepin on.

`C-x a' is bound to `abbrev-map', but its value is this:

(keymap
 (110 . expand-jump-to-next-slot)
 (112 . expand-jump-to-previous-slot)
 (39 . expand-abbrev)
 (101 . expand-abbrev)
 (45 . inverse-add-global-abbrev)
 (105 keymap
      (108 . inverse-add-mode-abbrev)
      (103 . inverse-add-global-abbrev))
 (43 . add-mode-abbrev)
 (103 . add-global-abbrev)
 (1 . add-mode-abbrev)
 (108 . add-mode-abbrev))

No entry for C-x, that I can see.

And in English:

key             binding
---             -------

C-a             add-mode-abbrev
'               expand-abbrev
+               add-mode-abbrev
-               inverse-add-global-abbrev
e               expand-abbrev
g               add-global-abbrev
i               Prefix Command
l               add-mode-abbrev
n               expand-jump-to-next-slot
p               expand-jump-to-previous-slot

i g             inverse-add-global-abbrev
i l             inverse-add-mode-abbrev

I don't see anything that would explain this in the Lisp sources, grepping for
`abbrev-map'. I'm curious what the answer will be.