From: Kenneth Whistler (kenw@sybase.com)
Date: Mon Sep 20 2004 - 15:07:56 CDT
Asmus responded:
> >It's a simple combining character. Even if you can't do arbitrary circles
> >around characters, you can take one character sequence and map it to the
> >glyph in a font. Systems that can't do even that need to be fixed.
>
> In other words, you would like to treat this as a mandatory ligature.
>
> To make this work in interchange, we need to get the buy-in from enough
> platform, application and font vendors that they want to support this and
> similar characters in that way (and fix their products where necessary).
>
> If we can get that kind of buy-in, then we could add this and other special
> purpose circled characters via the new "named sequences".
>
> Lacking such buy-in, the addition of these as characters becomes more
> appealing.
In addition, for something like a copyright symbol, there are
property issues to consider, particularly in a R-to-L context.
The sequence <heh, combining-circle> as an AL strong R-to-L
character following by a combining mark, which will inherit
the directionality of its base. So the sequence will be set to
<AL, AL> for the purposes of bidirectional formatting.
The question for any potential proposal of a "Saudi-Arabian
Copyright Sign" is whether its directional properties should be
strong right-to-left (i.e. equivalent to how <heh, combining-circle>
would behave) or should be neutral (bc=ON), as for U+00A9
COPYRIGHT SIGN. A demonstrable difference in directional properties
would strengthen the case for separate encoding, whereas if
the proposed characters is bc=AL, then the case is weaker.
Second, there is the question of cursive joining for Arabic.
I don't know anything in the Unicode Standard that states that
a combining enclosing mark breaks cursive ligation. It stands
to reason that it *should*, but I don't know anything that
requires it. Certainly the application of *other* combining
marks, including the regular Arabic vowel pointing, does *not*
break cursive connection. Since it would appear to be
basically undefined and implementation-dependent what would
happen to an Arabic letter if followed by a combining enclosing
mark as the standard is currently written, this could be another
good argument in favor of simply having a Saudi-Arabian Copyright
Sign as a distinctly encoded character.
Third, I don't like the proposed name, SAUDI-ARABIAN COPYRIGHT SIGN,
for this. In general, 10646 doesn't go the route of naming characters
after *countries*, even if their general use is restricted in
area. A name more descriptive simply of the symbol itself
would probably be more acceptable, e.g.:
ARABIC HAH COPYRIGHT SIGN
* used in Saudi Arabia
or even:
CIRCLED ARABIC LETTER HAH
* a copyright sign used in Saudi Arabia
--Ken
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