Re: Satem-Centum (Kentum) split

Hi
I am trying to sort out language relationships for myself. Somewhere
recently I read that 2 or 3 of the so-called Satem languages don't
involve just a single constant-pair change, (g' to s) but involve two
constant-pair changes, and so are not quite the same thing as the
classic definition. I was fairly certain this was said at Cyril's
site, or in Mallory's book. But I can't seem to find it. In sorting
out relationships, I had reason to wonder about the strength of the
classic classification of languages (satem, centum) and needed to
re-read this section. Does anyone know the reference, or know
specifically what was said (which languages involve two constants
switches, which involve one and what the additional constant pair is?).

Thanks,
Brent