>Oversight; I should have used the term 'grade' in both sentences. But
> > ============
> Zero degree of the two other vowels are *i and *u, not zero.
> > =======
> Zero grade of the PIE ablaut vowel < PPIE *a; e-grade in *pet-.
> Zero degree and Zero grade are two different things in your theory !?
> Is it what I have to understand ?