protocol-specific operations, such as charset-based content
      negotiation in HTTP.

      "UTF-8" [RFC-2279] and "UTF-16" (Appendix C.3 of [UNICODE] and
      Amendment 1 of [ISO-10646]) are the recommended values,
      representing the UTF-8 and UTF-16 charsets, respectively. These
      charsets are  preferred since they are supported by all conforming
      XML processors [REC-XML].

      If an application/xml entity is received where the charset
      parameter is omitted, no information is being provided about the
      charset by the MIME Content-Type header. Conforming XML processors
      MUST follow the requirements in section 4.3.3 of [REC-XML] which
      directly address this contingency. However, MIME processors which
      are not XML processors should not assume a default charset if the
      charset parameter is omitted from an application/xml entity.

      Since the charset parameter is authoritative, the charset is not
      always declared within an XML encoding declaration.  Thus, special
      care is needed when the recipient strips the MIME header and
      provides persistent storage of the received XML entity (e.g., in a
      file system).  Unless the charset is UTF-8 or UTF-16, the
      recipient SHOULD also persistently store information about the
      charset, perhaps by embedding a correct XML encoding declaration
      within the XML entity.













 
RFC 2376                    XML Media Types                    July 1998


   Encoding considerations:

      This media type MAY be encoded as appropriate for the charset and
      the capabilities of the underlying MIME transport. For 7-bit
      transports, data in both UTF-8 and UTF-16 is encoded in quoted-
      printable or base64.  For 8-bit clean transport (e.g., ESMTP,
      8BITMIME, or NNTP), UTF-8 is not encoded, but UTF-16 is base64
      encoded.  For binary clean transport (e.g., HTTP), no content-
      transfer-encoding is necessary.

   Security considerations:

      See section 4 below.

   Interoperability considerations:

      XML has proven to be interoperable for import and export from
      multiple XML authoring tools.

   Published specification: see [REC-XML]

   Applications which use this media type:

      XML is device-, platform-, and vendor-neutral and is supported by
      a wide range of Web user agents and XML authoring tools.

   Additional information:

      Magic number(s): none

      Although no byte sequences can be counted on to always be present,
      XML entities in ASCII-compatible charsets (including UTF-8) often
      begin with hexadecimal 3C 3F 78 6D 6C ("<?xml"), and those in
      UTF-16 often begin with hexadecimal FE FF 00 3C 00 3F 00 78 00 6D
      or FF FE 3C 00 3F 00 78 00 6D 00 (the Byte Order Mark (BOM)
      followed by "<?xml").  For more information, see Annex F of [REC-
      XML].

      File extension(s): .xml, .dtd
      Macintosh File Type Code(s): "TEXT"

   Person & email address for further information:

      Dan Connolly <connolly@w3.org>
      Murata Makoto (Family Given) <murata@fxis.fujixerox.co.jp>

   Intended usage: COMMON





 
RFC 2376                    XML Media Types                    July 1998


   Author/Change controller: