As an exercise in naturalistic sound change design, I'm trying to implement
the sound change rules for Early Slavic through Proto-Slavic as described
in Frederik Kortlandt's "From Proto-Indo-European to Slavic", but I am
finding some of them too vague to usefully implement. For example, in his
section 5.6 "final s" goes to h, but then in 5.9 we encounter "raising
before final s". Apart from the issue of where these final s's come from
that are conditioning the raising, I am unable to tell from the relevant
paragraph which vowels are raising, and to what they have been raised.

In short, does anyone know where I can find these rules already written in
X -> Y / Z_ format? Or is this period of the development of Slavic still
more art than science, with no sufficiently clear sound change rules having
been established to support such a formalization?

Thanks,
Amanda