>I have suggested the following analysis of the imperfect
>subjunctive *-se:- (ama:-re:-s, ppf.sbj. ama:vis-se:-s):
It could also be form other analogies:
(a) All other subjunctives have a long vowel before the s.
(b) No verb form (other than the verb to be) ends in short -es.
(c) Short -es everywhere else became -is (e.g gen singular 3rd decl.).
Analogy from the 1sg and 3 pl (where -em) did not change) restores the
quality of the vowel, and analogy from the ragged pattern of vowel quantity
in many other paradigms restores the quantity.
Peter