Cotemporality (messages received at the same time as sent).
Simultaneity (can both parties send messages at the same time or do
they have to take turns)
Sequentiality (can the turns get out of sequence).
Reviewability (can they review messages, after they have been first received).
Reviseability (can the producer edit the message privately before sending
Co-presence (can see the same things).
Visibility (can see each other).
Audibility (can hear each other)
Persistency (how long it remains
displayed).
Reflexivity (representing interactions).
Contextuality (keep the context with the message)