http://www.rfc-editor.org/rfc/rfc6122.txt
RFC 6122: Extensible Messaging and Presence Protocol (XMPP): Address Format, P. Saint-Andre2011-03-01T23:00:00-00:00This document defines the format for addresses used in the Extensible Messaging and Presence Protocol (XMPP), including support for non-ASCII characters. This document updates RFC 3920. [STANDARDS-TRACK]