Even in the case of Irish, the uppercase "S" denotes a distinctful variant of "s" . . .
No, it doesn't.
which should better be noted with some diacritic, such as a hacek or cedilla . . .
You're joking, right? Or is this the world's first proposal for orthographic reform of a language made by someone who knows nothing---really, nothing---about it?
Séamas Ó Brógáin ----------------
