zoned

If a player has has the zoned flag set, that player is considered 
to be zoned out (temporarily away from the MUD, although he/she might
still be connected to it). Anyone who pages or whispers to that player 
will see the player's away message. Type "help @away" for more 
information about setting your away message.

If a room or object is set zoned, then anyone can set something's zone 
to that object with the @zone command.