Re: Registration of new charset CP50220

[Masatoshi Kimura <VYV03354@nifty.ne.jp>]

(2010/09/04 4:50), Shawn Steele wrote:
> I don't think the registration needs an alias, unless someone's
> actually using that name already?

The "csCP50220" alias was added for MIB requirements. See
<http://mail.apps.ietf.org/ietf/charsets/msg01880.html>.

> If I understand the intent correctly, the intent here is to match
> Microsoft's 50220 behavior?  If so, I think that defining the
> "character sets" in terms of the JIS standards is a little bit odd.
> Instead I might consider pointing the character set mappings, like at
> http://www.unicode.org/Public/MAPPINGS/VENDORS/MICSFT/WINDOWS/ ? (Not
> sure if that completely works)

There is no official character set mappings for CP50220 (it it existed, 
the problem would be much less complicate).
Moreover, it will be insuffiecient to point a mapping table because 
CP50220 is a stateful encoding. A BNF or a decoding algorithm (like 
HTML5 spec) will be required. Defining in terms of the JIS standards is 
an easiest workaround.

> I'm not sure the comparison to shift_jis makes much sense.  They both
> encode Japanese, but 50220/iso-2022-jp are both stateful escape
> sequence based encodings, whereas shift_jis is "just" a double-byte
> code page.

The comparison is not a CP50220/ISO-2022-JP vs. Shift_JIS but a 
Shift_JIS vs. Windows-31J. It is required to express "characters 
extended by Windows Codepage 932" because only shift_jis variant 
(Windows-31J, Windows Codepage 932, or whatever) has the "official" 
mappings provided by Microsoft. Again, it would not be required if 
Microsoft provided an official mappings for CP50220.

-- 
VYV03354@nifty.ne.jp