On 8/11/05, Kazunari Hirano <[EMAIL PROTECTED]> wrote:
> Hi Art and all,
> Art - Arthit Suriyawongkul wrote:
> > Thai: CTL, LTR, HTL
> Thanks.
> When you say Thai is CTL, how is Thai text layout complex?
> I don't see exactly what CTL means, what is complex.
> Thai, Oriya, Urdu, Arabic, Hebrew and so on are called CTL languages.
> Why are they called CTL?  What are they complex about?
> :)


Sun has a very nice documentation on CTL. 
http://docs.sun.com/app/docs/doc/806-5583/6jej7sqe9?a=view

It addresses the fundamental characteristics of CTL languages and I am
going to repeat here.

* Bidirectional text--Arabic and Hebrew are written right to left, but
numbers and Roman-based characters are written left to right.
* Contextual analysis--each Arabic character has up to four display
representations. The representation glyph depends on its position in
the text.
* Ligatures--combinations of two or more Arabic characters can form a
different, single character.
Diacritics--diacritical marks placed above, below, or inside vowels
and consonants modify their tonal value.
* Character clusters--syllables and cells, especially in Thai, are
composed of several alphabetic elements, including vowels, consonants,
diacritics, and tone marks.
* Number and date formats--some Arabic countries use Hindi digits
rather than Arabic digits, and the Islamic calendar rather than the
Western calendar.


Korean is not CTL, because it is unidirectional - LTR. Regarding to
document layout, we had used VTL traditionally. However, it had been
replaced by HTL with modernization of society. Nowadays, we don't use
VTL anymore except for special case. In short, Korean is HTL/VTL.

Regards,
-- 
Jeongkyu Kim
OpenOffice.org Korean community lead

Official website http://ko.openoffice.org
Community forum  http://oooko.net/
Personal blog    http://oooko.net/gomme

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