MSG --- The MSG control pattern (2#10000000) indicates an asynchronous message. The encoding of the packet is context-dependent: MSG Modifiers: 2#0000 0001 means set up a temporary channel 2#0000 0010 means monitor the receiver <> VChan = 0 is the administrative channel VChan = 1 .. 254 are user-defined channels VChan = 255 is an extention byte, indicating that the next 4 bytes are <> That is: <> is to be read as "send Message contained in Rest using the protocol registered on the virtual channel {VsnGroup, ChId}.