>> "Stefan" == Stefan Monnier <monnier@iro.umontreal.ca> writes:

   >> Do you mean \usepackage[utf8]{inputenc}
   > Yes.

>> actual accented chars in the file).  Are you referring to the replacement
>> of "\alpha" with an "á" and things like that?
   >> Do you mean (set-input-method "TeX")? 

   > No, I mean the thing that visually replaces \alpha with an actual
   > á character (and converts it back when you save).

Can you give me any example, I mean a function which does this?

Aidan provided some code some time ago, TeX-escape-region which seems to
do what you mean: it replaces (back and forth) between \alpha and á. 
However there were some problems I don't recall precisely but the
function was not bijective. 

I not sure whether this code made it into GNU emacs. Or are you saying
there is another package with the same functionality?

   >> Besides sub and super indices were not supported.[1]

   > Not sure what you mean by that.


Oh in Latex you can have $u_k$ or $u^l$ where k is the sup and l the
super index.


Uwe