--- 1/draft-ietf-appsawg-mime-default-charset-03.txt 2012-05-28 12:15:48.045342945 +0200 +++ 2/draft-ietf-appsawg-mime-default-charset-04.txt 2012-05-28 12:15:48.057341986 +0200 @@ -1,20 +1,20 @@ Applications Area Working Group A. Melnikov Internet-Draft Isode Limited Updates: 2046 (if approved) J. Reschke Intended status: Standards Track greenbytes -Expires: October 24, 2012 April 22, 2012 +Expires: November 10, 2012 May 9, 2012 Update to MIME regarding Charset Parameter Handling in Textual Media Types - draft-ietf-appsawg-mime-default-charset-03 + draft-ietf-appsawg-mime-default-charset-04 Abstract 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 @@ -29,21 +29,21 @@ Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet- Drafts is at http://datatracker.ietf.org/drafts/current/. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." - This Internet-Draft will expire on October 24, 2012. + This Internet-Draft will expire on November 10, 2012. Copyright Notice Copyright (c) 2012 IETF Trust and the persons identified as the document authors. All rights reserved. This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (http://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents @@ -55,36 +55,37 @@ Table of Contents 1. Introduction and Overview . . . . . . . . . . . . . . . 3 2. Conventions Used in This Document . . . . . . . . . . . 3 3. New rules for default charset parameter values for text/* media types . . . . . . . . . . . . . . . . . . 3 4. Default charset parameter value for text/plain media type . . . . . . . . . . . . . . . . . . . . . . 4 5. Security Considerations . . . . . . . . . . . . . . . . 4 - 6. IANA Considerations . . . . . . . . . . . . . . . . . . 4 + 6. IANA Considerations . . . . . . . . . . . . . . . . . . 5 7. References . . . . . . . . . . . . . . . . . . . . . . 5 7.1. Normative References . . . . . . . . . . . . . . . . . 5 7.2. Informative References . . . . . . . . . . . . . . . . 5 Appendix A. Acknowledgements . . . . . . . . . . . . . . . . . . . 5 - Authors' Addresses . . . . . . . . . . . . . . . . . . 5 + Authors' Addresses . . . . . . . . . . . . . . . . . . 6 1. Introduction and Overview - [RFC2046] specified that the default charset parameter (i.e. the - value used when it is not specified) is "US-ASCII". [RFC2616] - changed the default for use by HTTP to be "ISO-8859-1". This - encoding is not very common for new text/* media types and a special - rule in HTTP adds confusion about which specification ([RFC2046] or - [RFC2616]) is authoritative in regards to the default charset for - text/* media types. + RFC 2046 specified that the default charset parameter (i.e. the value + used when the parameter is not specified) is "US-ASCII" (Section + 4.1.2 of [RFC2046]). RFC 2616 changed the default for use by HTTP + (Hypertext Transfer Protocol) to be "ISO-8859-1" (Section 3.7.1 of + [RFC2616]). This encoding is not very common for new text/* media + types and a special rule in the HTTP specification adds confusion + about which specification ([RFC2046] or [RFC2616]) is authoritative + in regards to the default charset for text/* media types. Many complex text subtypes such as text/html [RFC2854] and text/xml [RFC3023] have internal (to their format) means of describing the charset. Many existing User Agents ignore the default of "US-ASCII" rule for at least text/html and text/xml. 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. It does not change the defaults for any currently registered media type. @@ -125,20 +125,26 @@ 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. New subtypes of the "text" media type, thus, SHOULD NOT define a default "charset" value. If there is a strong reason to do so despite this advice, they SHOULD use the "UTF-8" [RFC3629] charset as the default. + Regardless of what approach is chosen, all new text/* registrations + MUST clearly specify how the charset is determined; relying on the + default defined in Section 4.1.2 of [RFC2046] is no longer permitted. + However, existing text/* registrations that fail to specify how the + charset is determined still default to US-ASCII. + Specifications covering the "charset" parameter, and what default value, if any, is used, are subtype-specific, NOT protocol-specific. Protocols that use MIME, therefore, MUST NOT override default charset values for "text/*" media types to be different for their specific protocol. The protocol definitions MUST leave that to the subtype definitions. 4. Default charset parameter value for text/plain media type The default charset parameter value for text/plain is unchanged from