http://www.rfc-editor.org/rfc/rfc2778.txt
RFC 2778: A Model for Presence and Instant Messaging, M. Day, J. Rosenberg, H. Sugano2000-02-01T23:00:00-00:00This document defines an abstract model for a presence and instant messaging system. It defines the various entities involved, defines terminology, and outlines the services provided by the system. This memo provides information for the Internet community.