(RFC 3994 published January 2005, subtype last updated January 2005)

MIME media type name: application
MIME subtype name: im-iscomposing+xml
Required parameters: (none)
Optional parameters: charset; Indicates the character encoding of
   enclosed XML.  Default is UTF-8.
Encoding considerations: Uses XML, which can employ 8-bit characters,
   depending on the character encoding used.  See RFC 3023 [4],
   section 3.2.
Security considerations: This content type is designed to carry
   information about current user activity, which may be considered
   private information.  Appropriate precautions should be adopted to
   limit disclosure of this information.
Interoperability considerations: This content type provides a common
   format for exchange of composition activity information.
Published specification: RFC 3994
Applications which use this media type: Instant messaging systems.
Additional information: none
Person & email address to contact for further information: Henning
   Schulzrinne, hgs&cs.columbia.edu
Intended usage: LIMITED USE
Author/Change controller: This specification is a work item of the
   IETF SIMPLE working group, with the mailing list address
   simple&ietf.org.
Other information: This media type is a specialization of
   application/xml RFC 3023 [4], and many of the considerations
   described there also apply to application/im-iscomposing+xml.