Re: ISO 2022

From: Erik van der Poel (
Date: Fri Oct 24 1997 - 12:55:24 EDT

Martin J. Dürst wrote:

> I will contact Prof. Shibano to investigate why JIS X 0208:1997 says
> that iso-2022-jp does not conform to ISO 2022.

RFC 1468 already says which part does not conform to ISO 2022:

   The JIS X 0208 standard was revised in 1990, to add two characters at
   the end of the table. Although ISO 2022 specifies special additional
   escape sequences to indicate the use of revised character sets, it is
   suggested here not to make use of this special escape sequence in
   ISO-2022-JP text, even if the two characters added to JIS X 0208 in
   1990 are used.

The additional escape sequence is ESC & @.

It is true that ISO 2022 does not require you to switch back to a single-byte
character set before the end of the line, but I don't think that this rule in
RFC 1468 is in non-conformance with ISO 2022. It is just an additional
restriction on top of ISO 2022. This rule was specified at the time, because
people were using Unix programs like "less" which did random access in the
file, and they didn't want to have to search all the way back to an escape
sequence just to figure out what the current character set was. So they put in
additional escape sequences at every line, so that "less" wouldn't have to
backtrack very far.

Erik van der Poel

Author, RFC 1468 (iso-2022-jp)

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