Re: [apps-discuss] Last Call: <draft-ietf-appsawg-mime-default-charset-03.txt> (Update to MIME regarding Charset Parameter Handling in Textual Media Types) to Proposed Standard

[t.petch <[e-mail]>]

---- Original Message -----
From: "Julian Reschke" <[e-mail]>
To: "t.petch" <[e-mail]>
Cc: "Barry Leiba" <[e-mail]>; "Ned Freed"
<[e-mail]>; <[e-mail]>
Sent: Friday, May 11, 2012 4:49 PM

> On 2012-05-11 14:59, t.petch wrote:
> > What charset should be used to inspect the content?  Should this be defined
in
> > this I-D?
> >
> > The new rules say that
> > "charset" parameter is not used for the defined
> >         subtype, because the charset information is transported inside
> >         the payload (such as in "text/xml")
> >
> >   But a charset is needed in order to read the payload and determine that
> > charset.  Catch-22?
> >...
>
> No. Just not trivial.
>
> See for instance <http://www.w3.org/TR/REC-xml/#sec-guessing>; HTML5 has
> similar (but surely more complex) rules.

Julian

Right, thanks for the reference.
"In the general case, this is a hopeless situation. It is not entirely hopeless
in XML, however, because XML limits the general case in two ways"

But ... that is saying that XML recognises the need to be able to auto-detect
the character encoding and is designed to do so.  This change to mime default
charset imposes the need to auto-detect on all future text/* where the encoding
is transported inside the payload, which the old rules did not.  Perhaps a
corner case not worth mentioning.

Tom Petch

> Best regards, Julian
>