Why isn't there a key equivalent to variable-binding-locus? As

in, a way to figure out where a particular keybinding is coming

from. For example,

    M-x key-binding-locus C-j

would evaluate to 'lisp-interaction-mode-map, which is the first

map in which C-j was found.

In terms of implementation, the process for finding a binding is

described in (info "(elisp) Searching Keymaps"):

    ...Here is a pseudo-Lisp description of the order and

    conditions for searching them:

     (or (cond

          (overriding-terminal-local-map

           (FIND-IN overriding-terminal-local-map))

          (overriding-local-map

           (FIND-IN overriding-local-map))

          ((or (FIND-IN (get-char-property (point) 'keymap))

       (FIND-IN-ANY emulation-mode-map-alists)

       (FIND-IN-ANY minor-mode-overriding-map-alist)

       (FIND-IN-ANY minor-mode-map-alist)

       (if (get-text-property (point) 'local-map)

           (FIND-IN (get-char-property (point) 'local-map))

         (FIND-IN (current-local-map))))))

         (FIND-IN (current-global-map)))

So implementing key-binding-locus would only be a small tweak of

the key lookup code: the first time you find the key, just return

the map you found it in, rather than the command it's supposed to

call.

Thanks,

Brian