--- In qalam@yahoogroups.com, "suzmccarth" <suzmccarth@...> wrote:
> The Tamil 99 keyboard only has the independent vowels displayed on
> the keyboard and these can be used to input both the independent or
> dependent vowels, depending on context. So now I am not sure why
> the independent and dependent vowels have been encoded separately
> Unicode. I suppose there must be a reason.

You can use the Tamil 99 keyboard to write independent vowels in the
middle of a word, though I don't know whether it's done. They'd be a
conceivable choice if there were a hiatus in a word, so it would be
risky to unify them. Across scripts, independent /a/ has a tendency
to become a consonant (it can be one in Devanagari, and tends to be
used in preference to the independent vowels for native words in S.E.
Asian scripts), and in some languages (e.g. Khmer) they can form
conjuncts with a preceding consonant. Historically, the Indian
Unicode encodings are based on ISCII, which unified the Brahmi-
derived scripts of India.

> If anyone knows i would
> be interested in hearing how it came about. What about the final
> forms of consonants in Hebrew of sigma in Greek.

There are exceptions to these conventions in both Greek and Hebrew,
and these exceptions force the separate encodings in Greek and Hebrew.