the XML media types also belong in the IETF media types tree.













 
RFC 2376                    XML Media Types                    July 1998


2  Notational Conventions

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in [RFC-2119].

3  XML Media Types

   This document introduces two new media types for XML entities,
   text/xml and application/xml.  Registration information for these
   media types are described in the sections below.

   Every XML entity is suitable for use with the application/xml media
   type without modification.  But this does not exploit the fact that
   XML can be treated as plain text in many cases.  MIME user agents
   (and web user agents) that do not have explicit support for
   application/xml will treat it as application/octet-stream, for
   example, by offering to save it to a file.

   To indicate that an XML entity should be treated as plain text by
   default, use the text/xml media type.  This restricts the encoding
   used in the XML entity to those that are compatible with the
   requirements for text media types as described in [RFC-2045] and
   [RFC-2046], e.g., UTF-8, but not UTF-16 (except for HTTP).

   XML provides a general framework for defining sequences of structured
   data.  In some cases, it may be desirable to define new media types
   which use XML but define a specific application of XML, perhaps due
   to domain-specific security considerations or runtime information.
   This document does not prohibit future media types dedicated to such
   XML applications. However, developers of such media types are
   recommended to use this document as a basis.  In particular, the
   charset parameter should be used in the same manner.

   Within the XML specification, XML entities can be classified into
   four types.  In the XML terminology, they are called "document
   entities", "external DTD subsets", "external parsed entities", and
   "external parameter entities".  The media types text/xml and
   application/xml can be used for any of these four types.

3.1 Text/xml Registration

   MIME media type name: text

   MIME subtype name: xml

   Mandatory parameters: none





 
RFC 2376                    XML Media Types                    July 1998


   Optional parameters: charset

      Although listed as an optional parameter, the use of the charset
      parameter is STRONGLY RECOMMENDED, since this information can be
      used by XML processors to determine authoritatively the character
      encoding of the XML entity. The charset parameter can also be used
      to provide protocol-specific operations, such as charset-based
      content negotiation in HTTP.  "UTF-8" [RFC-2279] is the
      recommended value, representing the UTF-8 charset. UTF-8 is
      supported by all conforming XML processors [REC-XML].

      If the XML entity is transmitted via HTTP, which uses a MIME-like
      mechanism that is exempt from the restrictions on the text top-
      level type (see section 19.4.1 of HTTP 1.1 [RFC-2068]), "UTF-16"
      (Appendix C.3 of [UNICODE] and Amendment 1 of [ISO-10646]) is also
      recommended.  UTF-16 is supported by all conforming XML processors
      [REC-XML].  Since the handling of CR, LF and NUL for text types in
      most MIME applications would cause undesired transformations of
      individual octets in UTF-16 multi-octet characters, gateways from
      HTTP to these MIME applications MUST transform the XML entity from
      a text/xml; charset="utf-16" to application/xml; charset="utf-16".

      Conformant with [RFC-2046], if a text/xml entity is received with
      the charset parameter omitted, MIME processors and XML processors
      MUST use the default charset value of "us-ascii".  In cases where
      the XML entity is transmitted via HTTP, the default charset value