From: John Hudson (john@tiro.ca)
Date: Fri Jan 04 2008 - 04:39:14 CST
arno wrote:
> What they propose is
> a letter that is non-joining when
> a) initial
> b) final
> c) isolated i.e. final after a right-joining letter
> but is transparent
> after a dual joining letter AND at the same time
> before a dual- or right joining letter.
Correct.
> (( I disagree, saying it is transparent only between lam and alef,
> sitting above a connecting stroke in all other cases.
> But this can wait till we have settled the first question.))
> The questions are:
>
> Can this be done in Unicode?
>
> Can this be achieved by just changing the characteristics of U+0621?
There is another way of looking at it, which produces a different question:
Does anything need to be done in Unicode about it?
As you indicated, in some conventional usage the hamza is dividing (a better term, I
think, than non-joining), while in other conventional usage it is transparent according to
context. So whichever way it is defined in Unicode, some mechanism must exist for the
alternative usage: if it is defined as dividing, a mechanism is needed to make it display
as transparent in appropriate contexts; if it is defined in some way as transparent then a
mechanism is needed to make it display as dividing.
I consider the variance in usage a matter of display, i.e. I think it would be a big
mistake to use a different character for the hamza to achieve a different appearance or
shaping behaviour, as this reduces ease of text comparison, spellchecking, sorting, etc.
I suspect that inertia will decide this issue: it is possible to resolve the display of
transparent hamza at the font level on top of the existing definition of U+0621, so I
doubt if the UTC will see much impetus to make changes that might cause problems for
existing implementations.
Of course, different font and layout models have different capabilities. I know OpenType
better than the others, and in that context there is not only the capability to resolve
display of transparent hamza contextually but also user-controlled mechanisms to inhibit
such display if a dividing hamza is preferred (e.g. turning off discretionary contextual
alternates or treating the dividing hamza as a stylistic variant).
John Hudson
PS. I may not respond to further comments very promptly due to other commitments.
-- Tiro Typeworks www.tiro.com Gulf Islands, BC tiro@tiro.com The Lord entered her to become a servant. The Word entered her to keep silence in her womb. The thunder entered her to be quiet. -- St Ephrem the Syrian
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