Registration of the text/red MIME Sub-Type
RFC 4102

Document Type RFC - Proposed Standard (June 2005; Errata)
Updated by RFC 6354
Author Paul Jones 
Last updated 2013-03-02
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IESG IESG state RFC 4102 (Proposed Standard)
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Network Working Group                                           P. Jones
Request for Comments: 4102                           Cisco Systems, Inc.
Category: Standards Track                                      June 2005

               Registration of the text/red MIME Sub-Type

Status of This Memo

   This document specifies an Internet standards track protocol for the
   Internet community, and requests discussion and suggestions for
   improvements.  Please refer to the current edition of the "Internet
   Official Protocol Standards" (STD 1) for the standardization state
   and status of this protocol.  Distribution of this memo is unlimited.

Copyright Notice

   Copyright (C) The Internet Society (2005).


   This document defines the text/red MIME sub-type.  "Red" is short for
   redundant.  The actual RTP packetization for this MIME type is
   specified in RFC 2198.

1.  Introduction

   Text is an important component of any multimedia communication
   system.  Like audio, the transport of text can benefit from the use
   of redundancy in order to improve reliability and end-user

   RFC 2198 [1] defines an RTP [2] payload format for redundant audio
   data.  The format defined in that document is quite suitable for
   providing redundancy for text, as well as audio.

   RFC 4103 [8] specifies one usage of RFC 2198 and the text/red MIME
   type for the transport of redundant text data.

   This memo provides the MIME sub-type registration information for
   text/red.  While this document focuses on the use of this MIME sub-
   type in SDP [5], the application of this MIME sub-type is not
   restricted to SDP.

Jones                       Standards Track                     [Page 1]
RFC 4102                 text/red MIME Sub-Type                June 2005

2.  Conventions Used in This Document

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   document are to be interpreted as described in RFC 2119 [3].

3.  IANA Considerations

   One new MIME sub-type has been registered by the IANA, as described

   MIME media type name: text

   MIME subtype name: RED

   Required parameters:
      rate: the RTP clock rate of the payload carried within the RTP
      packet.  Typically, this rate is 1000, but other rates MAY be
      specified.  This parameter MUST be set equal to the clock rate of
      the text payload format carried as the primary encoding.

      pt: a comma-separated ordered list of RTP payload types
      enumerating the primary, secondary, etc., in accordance with RFC
      2198.  Because comma is a special character, the list MUST be a
      quoted-string (enclosed in double quotes).  For static payload
      types, each list element is simply the type number.  For dynamic
      payload types, each list element is a mapping of the dynamic
      payload type number to an embedded MIME content-type specification
      for the payload format corresponding to the dynamic payload type.
      The format of the mapping is:

               dynamic-payload-type "=" content-type

      If the content-type string includes a comma, then the content-
      type string MUST be a quoted-string.  If the content-type string
      does not include a comma, it MAY still be quoted.  Because it is
      part of the list, which must itself be a quoted-string, the
      quotation marks MUST be quoted with backslash quoting as specified
      in RFC 2045 [4].  If the content-type string itself contains a
      quoted-string, then the requirement for backslash quoting is
      recursively applied.

   Optional parameters: ptime, maxptime (these attributes are originally
      defined in RFC 2327 [5] and RFC 3267 [6], respectively)

   Restrictions on Usage:
      This type is defined only for transfer via RTP.
      It shall not be defined for a storage format.

Jones                       Standards Track                     [Page 2]
RFC 4102                 text/red MIME Sub-Type                June 2005

   Encoding considerations:
      See restrictions on Usage above; this section is included per
      the requirements in RFC 3555 [7].

   Security considerations: Refer to section 5 of RFC 4102.

   Interoperability considerations: none

   Published specification: RFC 2198

   Applications which use this media type:
      Text streaming and conferencing tools.

   Additional information: none

   Person & email address to contact for further information:
      Paul E. Jones

   Intended usage: COMMON

      Paul E. Jones

   Change Controller:
      AVT Working Group delegated from the IESG

4.  Mapping to SDP Parameters

   The information carried in the MIME media type specification has a
   specific mapping to fields in the Session Description Protocol (SDP)
   [5], which is commonly used to describe RTP sessions.  When SDP is
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