Most Auto-Away scripts use this (rather annoying) method to announce when a user is away.

Client to Server: PRIVMSG #channel :ACTION is Away (Auto-Away after 10 minutes)
Server to Each Client on #channel: :SomDumFoo!:Lamest@dummy.aol.com PRIVMSG #channel :ACTION is Away (Auto-Away after 10 minutes)

Client to Server: PRIVMSG #channel :ACTION is Back (After 15 minutes Away)
Server to Each Client on #channel: :SomDumFoo!:Lamest@dummy.aol.com PRIVMSG #channel :ACTION is Back (After 15 minutes Away)

Personally, I prefer to use the SERVER /away command, and inform only those who are specifically interested in my away status.

Client to Server: AWAY Absorbing some natural light.
Server to Single Client who types /whois Raccoon or /msg Raccoon <text>
Raccoon_ is away: Absorbing some natural light. (mirc format)

This non-intrusive Away Status is most universally accepted, least bandwidth, and least server resource using method... and comes already built into mIRC and the IRCd (server). No scripting required, just send your /away <reason> command to the server, and /away when you return to unset your Away Status.

- Raccoon


Well. At least I won lunch.
Good philosophy, see good in bad, I like!