mm-charset-override-alist

mm-charset-override-alist is a variable defined in `mm-util.el'.
Its value is

((gb2312 . gbk)
 (iso-8859-1 . windows-1252)
 (iso-8859-8 . windows-1255)
 (iso-8859-9 . windows-1254))

Documentation:
A mapping from undesired charset names to their replacement.

You may add pairs like (iso-8859-1 . windows-1252) here,
i.e. treat iso-8859-1 as windows-1252. windows-1252 is a
superset of iso-8859-1.

You can customize this variable.

This variable was introduced, or its default value was changed, in version 22.1 of Emacs.