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Re: internationalization/ISO10646 question

From: Chris Newman <Chris.Newman@Sun.COM>
Date: Fri, 03 Jan 2003 17:56:59 -0800
To: MURATA Makoto <murata@hokkaido.email.ne.jp>
Cc: Marcin Hanclik <mhanclik@poczta.onet.pl>, ietf-charsets@iana.org
Message-id: <2147483647.1041616619@nifty-jr.west.sun.com>

begin quotation by MURATA Makoto on 2003/1/3 11:11 +0900:
> I do not agree on this claim yet.  In particular, I'm concerned with the
> 6-byte  representation of non-BMP characters.  When non-BMP characters
> become common,  what will happen?

Software which is fully UTF-8 native will likely work just fine.  UTF-8 
aware software already has support for variable width characters, whether 
it is 2, 3, 4, 5 or 6 octets in the variable width character, the code path 
used should be the same and will have already been tested.

Software which converts UTF-8 to UCS-2 will break completely.  There may be 
more of this junk out there than one might hope.

Software which converts UTF-8 to UTF-16 may not work because a lot of 
UTF-16 software has never been tested with variable-width characters.

That's actually the most serious flaw in UTF-16.  It's a variable width 
encoding, but the variable width characters are an uncommon case 
(currently).  That means all the code to support non-16 bit characters in 
UTF-16 is an uncommon case and those codepaths haven't been tested (if they 
exist).  Thus you can expect deployed UTF-16 based software to break in 
various ways as non-BMP characters show up.

Unfortunately, I'm afraid the majority of software will fall in the latter 
two categories.

                - Chris
Received on Friday, 3 January 2003 21:03:40 UTC

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