Automatic recognition of some specific coding systems

["Jürgen Hartmann" <juergen_hartmann_@hotmail.com>]

Most of the text files that I have to work with are encoded with one
of the coding systems

   utf-8-unix
   latin-9-unix
   cp850-dos

Therefore, it was very convenient for me that the version 22.3 of
Emacs was (after some minor configuration) perfectly able to
automatically recognize these coding systems from the contents of the
respective files. As I understand, this was possible because in that
old Emacs version these tree systems were associated with three
different coding categories, i.e.

   coding-category-utf-8
   coding-category-iso-8-1   (meanwhile depreciated)
   coding-category-ccl

respectively.

Now switching to Emacs 24.4, I found that two of these coding systems,

   latin-9-unix
   cp850-dos

were bunched together into the category

   coding-category-charset

presumably with the consequence that I have to choose which one of
these two systems will not be automatically recognized any more.

Is this conclusion correct?

If yes, this would be a big regression from my point of view, so I am
very interested in any kind of workaround.
(If this has to be done by reimplementing cp850 via CCL, it would be
great to get some (link to a) tutorial on this topic.)

It is clear that there are coding systems that can not be
distinguished just by analyzing the encoded text. But from the
experience with former versions of Emacs I know that this particular
problem is not ill-posed.

Therefore, I would greatly appreciate any help.

Juergen