online property
current online status of the user; if this is a group or a p2p topic, it's user's online status in the topic, i.e. if the user is attached and listening to messages; if this is a response to a 'me' query, it tells if the topic is online; p2p is considered online if the other party is online, not necessarily attached to topic; a group topic is considered online if it has at least one active subscriber.
Implementation
bool? online;