(messages received at the same time as sent).
(can both parties send messages at the same time or
do they have to take turns)
(can the turns get out of sequence).
(can they review messages, after they have been
(can the producer edit the message privately before
(can see the same things).
(can see each other).
(can hear each other)
Clark & Brennan
(how long it remains displayed).
(keep the context with the message)