Parameter Name:  FEATURE

 Purpose:  To specify a feature or features of a conference or
 broadcast system.

 Format Definition:  This property parameter is defined by the
 following notation:

 featureparam = "FEATURE" "=" featuretext *("," featuretext)
 featuretext  =  ("AUDIO" /     ; Audio capability
 "CHAT" /      ; Chat or instant messaging
 "FEED" /      ; Blog or Atom feed
 "MODERATOR" / ; Moderator dial-in code
 "PHONE" /     ; Phone conference
 "SCREEN" /    ; Screen sharing
 "VIDEO" /     ; Video capability
 x-name /      ; Experimental type
 iana-token)   ; Other IANA registered type

 Description:  This property parameter MAY be specified on the
 "CONFERENCE" property.  Multiple values can be specified.  The
 "MODERATOR" value is used to indicate that the property value is
 specific to the owner/initiator of the conference and contains a
 URI that "activates" the system (e.g., a "moderator" access code
 for a phone conference system that is different from the "regular"
 access code).

 Example:

 CONFERENCE;VALUE=URI;FEATURE=AUDIO:rtsp://audio.example.com/
 event
 CONFERENCE;VALUE=URI;FEATURE=AUDIO,VIDEO:http://video-chat.exam
 ple.com/;group-id=1234