co: Repeat last seen PubSIC.
co ccom: Repeat last received private SIC.
co keyname: Repeat last seen SIC on keyname.
However I don't know if the system can distinguish between players not seeing a SIC because they were not in signal or no. The concept I had in mind is a player is in signal, gets the SIC, but is either disconnected or then disconnects and wants to check if they missed a message while they were technically still connected and in signal.