> I suggest the following variation of it:
>
> 	 doc: /* Return a list describing the argument FILE-OR-BUFFER.
>
>   If FILE-OR-BUFFER is a file name, return information about that file.
...
>   given depends on your version of that database.  Often the MIME type is
>   less exact than the description.  */)

I used this description.

> Two more comments:
>
>  . I am not sure you need to push the file-or-buffer dichotomy to the
>    C level.  It is easy enough to do that in Lisp, or even in the
>    application, for that matter.  Why complicate a primitive to do
>    such a simple job?

Ok, removed it.

>  . You didn't say in the doc string whether MIME-ENCODING is
>    guaranteed to be a valid Emacs coding-system.  I think a user will
>    be desperate to know that.

Did like Stefan sugested, return a string.

Also improved GCPRO stuff, like Andreas suggested.

-- 
Joakim Verona