Why is TAMIL SIGN VIRAMA (pulli) not Alphabetic?

[Doug Ewell via Unicode]

Richard Wordingham wrote:

>>> The effects of virama that spring to mind are:
>>>
>>> (a) Causing one or both letters on either side to change or combine
>>> to indicate combination;
>>>
>>> (b) Appearing as a mark only if it does not affect one of the
>>> letters on either side;
>>>
>>> (c) Causing a left matra to appear on the left of the sequence of
>>> consonants joined by a sequence of non-visible viramas.
>>
>> Most of these don't apply to Tamil, of course.
>
> They all apply to க்ஷே <U+0B95, U+0BCD, U+0BB7, U+0BC7> TAMIL
> SYLLABLE KSSEE. There are four other named syllables where they all
> apply.

And several others where they do not. TUS explains that visible
puḷḷi is the general rule in Tamil, and conjunct ligatures are the
exception.

I should have written "These mostly don't apply to Tamil, of course."

In any case, Ken has answered the real underlying question: a process
that checks whether each character in a sequence is "alphabetic" is
inappropriate for determining whether the sequence constitutes a word.
 
--
Doug Ewell | Thornton, CO, US | ewellic.org