From: Kenneth Whistler (kenw@sybase.com)
Date: Fri Apr 07 2006 - 18:11:46 CST
> >> Well, the implementations is (as far as I can tell), not quite
> >> automatic...
> >
> > Correct.
>
> So where is the non-automatic part? I haven't noticed any mirroring
> features in OpenType lay-out.
Despite many people's attempts to force things otherwise,
the Unicode Standard is not a glyph, rendering, or text layout
standard -- it is a character encoding standard.
> >> Also, when Greek (for instance) is written in the ancient
> >> boustrophedon way, the glyphs are mirrored on every second
> >> line of a paragraph (if not the whole text, I'm not sure). Yet,
> >> Greek letters are not given the bidi-mirrored property.
> >
> > Correct. And likewise there is no need to give Phaistos Disc
> > symbols Bidi_Mirrored=Y.
>
> But the situations are not the same. Modern Greek has inherent
> directionality - is it used in modern Arabic mathematics?
How is that of relevance to the boustrophedon issue for ancient Greek?
And if you don't like the Greek example, then refer to Old Italic
or to several others of the ancient Mediterranean scripts -- which
also demonstrate this glyph reversal to face the direction of
writing. Or Egyptian hieroglyphics, for that matter.
> If the Phaistos
> disk characters had inherent directionality, it would be right-to-left.
Also irrelevant.
> Would it be better to encode two sets - left-to-right and right-to-left?
No. One set, whether we are talking about letters or symbols. The
fact that for a long time, across a wide area, writing systems
flipped letters and symbols around a horizontal axis to match
the direction of the writing is not relevant to identity of the
characters per se.
> (This would make a mess of searching for substrings, and, far more
> importantly, would be a very bad precedent for hieroglyphics.)
Correct.
>
> As for boustrophedon, Unicode support is very poor.
Unicode "support" for boustrophedon is non-existent: as designed.
> You would also have to
> do your own line-breaking.
You have to "do your own line-breaking" in any case. In *all* cases,
in fact. The Unicode Standard does *not* tell anyone how they
have to break lines of text in any script or symbology.
And
if I
want
to b
reak
tex
t th
s wa
y I
can.
UAX #14 does provide a complete set of linebreaking properties that
can be used to determine potential linebreaking opportunities based
on character properties alone -- but it is up to an application to
implement algorithms based on such properties (or not). And then it
is up to users to make use of the formatting and text flowing
capabilities of those applications to accomplish whatever they
need to do with text.
So I think the correct statement is that text editing and page
layout application support for boustrophedon is poor.
Which is hardly surprising, because it isn't used in any modern writing
gnitirw rof rehtie ,hcaorppa cimonogre na yllaer t'nsi ti -- metsys
or particularly for reading in modern contexts. Boustrophedon
yllaitnesse era hcihw smelborp gnitirw tneicna niatrec devlos
not relevant to modern uses of writing.
--Ken
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