Re: message/utf-8-headers (was Re: [EAI] Poll for MIME type - revised schedule and details)

["Charles Lindsey" <chl at clerew.man.ac.uk>]

On Fri, 17 Aug 2007 20:02:17 +0100, Chris Newman <Chris.Newman at Sun.COM>  
wrote:

> With my former document author hat on, there were two reasons I switched  
> to "message" from "text" for that media type.
>
> First, return-of-headers is primarily useful as a correlation  
> mechanism.  It's undesirable for a correlation mechanism to be  
> transformed in a way that might break the correlation.  Using a text/*  
> type with a charset=* parameter invites such transformation of the  
> charset and makes it unclear what's expected of a client that's doing  
> correlation (e.g. would it have to support text/international-header for  
> all the charsets mentioned in RFC 2049 for minimal MIME compliance?).

OK, so omit the charset parameter, and state up-front that the charset  
MUST be utf-8. Or say that if charset is present it MUST be of the form  
charset=utf-8 (the only advantage of having a charset parameter at all is  
that some existing agents might be kind enough to act on it - but then  
DSNs will normally be sent to people with upgraded MUAs, even if some  
intermediate hop isn't).
> Second, message headers are fundamentally content related to a  
> "message". After discussing it with other MIME experts, we felt the name  
> text/rfc822-headers was probably a design error and it should have been  
> a message content type.  So the change was deliberate on that front as  
> well.

It was always am oddity that text/rfc822-headers was used originally, but  
now it is there noone can complain if the new DSNs use  
text/utf8-headers/whatever. The disadvantage of using  
message/rfc822-headers is that some agents will fail to handle it properly  
when downgrading for some non-8BITMIME systems (sendmail will just leave  
it as 8bit, for example). That is hardly robust. But every agent should be  
able to downgrade a text type in that situation.


> I agree this should go on the issue list to gauge WG rough consensus on  
> the topic.

+1

--
Charles H. Lindsey ---------At Home, doing my own thing------------------------
Tel: +44 161 436 6131 ;                      
   Web: http://www.cs.man.ac.uk/~chl
Email: chl at clerew.man.ac.uk      Snail: 5 Clerewood Ave, CHEADLE, SK8 3JU, U.K.
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