Fwd: New Version Notification for draft-murata-kohn-lilley-xml-03

[Chris Lilley]

On Friday, September 25, 2009, 1:58:56 PM, Julian wrote:

JR> Julian Reschke wrote:
>> Chris Lilley wrote:
>>> ...
>>> which also brings advice on the use of the charset parameter into line 
>>> with current practice. In brief, the charset parameter should only be 
>>> added if it agrees with the xml encoding declaration. In the absence 
>>> of an explicit charset parameter, the encoding specified by the xml 
>>> encoding declaration is used. (This is a change from RFC 3023, which 
>>> required enforcing us-ascii in that case).
>>> ...

>> Clarifying... this appears to apply only to application/xml, not 
>> text/xml, right?
>> ...

JR> Furthermore, this was already the case in RFC 3023, so is there any 
JR> change at all?

RFC 3023 on application/xml:

Optional parameters: charset

  Although listed as an optional parameter, the use of the charset
  parameter is STRONGLY RECOMMENDED, since this information can be
  used by XML processors to determine authoritatively the charset of
  the XML MIME entity. The charset parameter can also be used to
  provide protocol-specific operations, such as charset-based content
  negotiation in HTTP.


ID on application/xml:

Optional parameters: charset

  Although listed as an optional parameter, the use of the charset
  parameter, when the charset is reliably known and agrees with the
  encoding declaration, is RECOMMENDED, since this information can be
  used by non-XML processors to determine authoritatively the charset
  of the XML MIME entity. The charset parameter can also be used to
  provide protocol-specific operations, such as charset-based content
  negotiation in HTTP.


So, instead of being a STRONGLY RECOMMENDED and mainly for use by XML
parsers, the http charset is now only recommended if it says the same
as the xml (combination of the encoding declaration, the bom, and the
Appendix-F sniffing) and being mainly aimed at non xml processors. It
therefore becomes a redundant, non-conflicting source of encoding
information, aimed at a different level in the stack.

I would say that the change in emphasis of the http charset parameter
is the major change in this document. In particular, idf the server
does not reliably know the encoding of xml entitires it should not add
a charset parameter.
  
-- 
 Chris Lilley                    mailto:chris at w3.org
 Technical Director, Interaction Domain
 W3C Graphics Activity Lead
 Co-Chair, W3C Hypertext CG