jka-compr-mode-alist-additions

jka-compr-mode-alist-additions is a variable defined in `jka-cmpr-hook.el'.
Its value is

(("\\.tgz\\'" . tar-mode)
 ("\\.tbz2?\\'" . tar-mode)
 ("\\.txz\\'" . tar-mode))

Documentation:
List of pairs added to `auto-mode-alist' when installing jka-compr.
Uninstalling jka-compr removes all pairs from `auto-mode-alist' that
installing added.

If you set this outside Custom while Auto Compression mode is
already enabled (as it is by default), you have to call
`jka-compr-update' after setting it to properly update other
variables. Setting this through Custom does that automatically.

You can customize this variable.

This variable was introduced, or its default value was changed, in version 24.4 of Emacs.