Fortunatov's Law and tolkAppiyar's rules

[Vidhyanath Rao]

Miguel Carrasquer Vidal <mcv at WXS.NL> wrote:
>         *s^ (RUKI)  *k^ (SATEM)
> Iran.   s^          s < c

Does this mean that in Iranian, s>h and c>s occurred simultaneously,
without c becoming a shibilant first? I thought that assibiliztion of
c typically went through an `sh' stage first.

The fundemental question is the historical sequence of the three
changes in Iranian, without any two sounds even getting mixed up.
I don't see how to do it, if we insist that RUKI-s was always sh in
Iranian.

Regards
-Nath