From: Asmus Freytag (asmusf@ix.netcom.com)
Date: Fri Jan 09 2009 - 02:40:07 CST
On 1/8/2009 6:39 PM, Christopher Fynn wrote:
> ... there are already cell phones available in Tibet which use a
> pre-composed Tibetan character set:
> <http://www.actapress.com/PaperInfo.aspx?PaperID=30325>.
As long as these Tibetan character sets can't actually express something
that can't also be expressed in the standard Unicode encoding of
Tibetan, there's no issue here. The requirement is to losslessly convert
and roundtrip the text, not the code element. In particular, if they are
true pre-composed characters it should always be possbile to transcode
them using their decomposition in Unicode and then to compose back on
re-conversion.
The only issue arises, when these conversions aren't unique - as was the
case with converting from shaped, visual ordered Arabic to Unicode's
implictly ordered and implicitly shaped Arabic. At that point, pressure
arose to add compatibility characters for positional presentation forms
in order to allow lossless transcoding of legacy data.
A./
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