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Re: Charset mandatory in unix/linux

2006-03-26 13:37:10

On Sun March 12 2006 10:10, ned+ietf-822(_at_)mrochek(_dot_)com wrote:

(cc'ing the ietf-types list since this doesn't seem like an appropriate topic
for ietf-822)
[this response to types, cc to 822, Reply-To set to types]

[Jacob Palme wrote] 
The charset parameter is mandatory in the MIME content-type

Actually, I don't know of a single case where this is true. All media type
pararameters are either type or subtype specific, so there is no general rule
that applies to all charset parameters. Nevertheless, the charset parameters
that attach to the text top-level type are optional, as is the charset
parameter on application/xml.

What about text/directory and application/shf+xml (RFCs 2425 and
4194 respectively)?

RFC 2425:

5.3.  Required parameters

   Required parameters: charset

RFC 4194:

9.  IANA Considerations

   This section contains the registration information for the MIME type
   to SHF.  The media type has been chosen to comply with the guidelines
   in [4].

   o  Registration: application/shf+xml
   o  MIME media type name: application
   o  MIME subtype name: shf+xml
   o  Required parameters: charset

   Required parameters: charset

   This parameter must exist and must be set to "UTF-8".  No other
   character sets are allowed for transporting SHF data.  The character
   set designator MUST be uppercase.

[so in the latter case, the parameter is mandatory but conveys no
useful information as the charset is fixed, i.e. known a priori for
each instance of the media type, rather than variable...
4194 also conflicts with established usage of charset parameter
values as specified in RFC 2046: "Unlike some other parameter values,
the values of the charset parameter are NOT case sensitive" (That's
for text, but having case-sensitivity of the values FOR A GIVEN
PARAMETER ATTRIBUTE vary with type/subtype greatly complicates
parsing).  Sigh...]