Subject: [apps-discuss] I-D Action: draft-ietf-appsawg-mime-default-charset-01.txt

From: [email-masked]
Date: Fri, 30 Mar 2012 05:52:28 -0700

A New Internet-Draft is available from the on-line Internet-Drafts directories. This draft is a work item of the Applications Area Working Group Working Group of the IETF.

	Title           : Update to MIME regarding Charset Parameter Handling in Textual Media Types
	Author(s)       : Alexey Melnikov
                          Julian F. Reschke
	Filename        : draft-ietf-appsawg-mime-default-charset-01.txt
	Pages           : 6
	Date            : 2012-03-30

   This document changes RFC 2046 rules regarding default charset
   parameter values for text/* media types to better align with common
   usage by existing clients and servers.

Editorial Note (To be removed by RFC Editor)

   Discussion of this draft should take place on the Apps Area Working
   Group mailing list ([email-masked]), which is archived at
   <http://www.ietf.org/mail-archive/web/apps-discuss>.

A URL for this Internet-Draft is:
http://www.ietf.org/internet-drafts/draft-ietf-appsawg-mime-default-charset-01.txt

Internet-Drafts are also available by anonymous FTP at:
ftp://ftp.ietf.org/internet-drafts/

This Internet-Draft can be retrieved at:
ftp://ftp.ietf.org/internet-drafts/draft-ietf-appsawg-mime-default-charset-01.txt

---

From: Bill McQuillan <[email-masked]>
Date: Fri, 30 Mar 2012 14:19:48 -0700

In section 3:

----------
   In order to improve interoperability with deployed agents, "text/*"
   media type registrations SHOULD either

   a.  specify that the "charset" parameter is not used for the defined
       subtype, because the charset information is transported inside
       the payload (such as in "text/xml"), or
   b.  require explicit unconditional inclusion of the "charset"
       parameter eliminating the need for a default value.

   In accordance with option (a), above, registrations for "text/*"
   media types that can transport charset information inside the
   corresponding payloads (such as "text/html" and "text/xml") SHOULD
   NOT specify the use of a "charset" parameter, nor any default value,
   in order to avoid conflicting interpretations should the charset
   parameter value and the value specified in the payload disagree.
----------

Doesn't option (a) actually mean that a new default charset is
now defined, perhaps called "embedded-ascii", in which all octets
with values less than 128 must have the same meaning as the
correspondding ASCII values and that all octet values greater
than 127 may be ignored? This would allow naively processing a
newly specified text/* type by displaying the content first using
the "embedded-ascii" charset (ignoring non-ascii octets) and,
hopefully, finding, by eye, the actual charset specified within
and then re-displaying the content using that discovered charset.

For instance how would a newly specified type similar to
text/html with a document using the internal charset of "ebcdic"
be handled? The current specification would deal with this merely
by ensuring that a "charset=ebcdic" appeared in the Content-Type
Mime field and also within the document itself.

-- 
Bill McQuillan <[email-masked]>

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From: Larry Masinter <[email-masked]>
Date: Fri, 30 Mar 2012 15:52:57 -0700

RFC 2397 defaults media type of "data:" URIs to text/plain;charset=US-ASCII. 

Should this be updated to default to utf8?

---

From: Alexey Melnikov <[email-masked]>
Date: Sat, 31 Mar 2012 01:07:56 +0200

> Should this be updated to default to utf8?
I don't think so, unless there is WG consensus to change the default for 
text/plain in general. And so far I haven't seen one.

---

From: Ned Freed <[email-masked]>
Date: Sat, 31 Mar 2012 21:44:06 -0700 (PDT)

> Should this be updated to default to utf8?

I'm not entirely sure of all the ramifications, but they are minimal this
sound like a really good idea to me.

				Ned

---

From: Ned Freed <[email-masked]>
Date: Sat, 31 Mar 2012 21:45:28 -0700 (PDT)

> text/plain in general. And so far I haven't seen one.

How does this relate to the default for text/plain? I presume this default
would only apply if no content-type was specified.

				Ned