In order to see their chat status (which can be one of ``online'', ``offline'',
and several ``away'' or ``do not disturb'' states), a user needs to subscribe to
the other user's status. The mechanism behind this is called
In order to see their chat status (which can be one of ``online'', ``offline'',
and several ``away'' or ``do not disturb'' states), a user needs to subscribe to
the other user's status. The mechanism behind this is called