Upon receiving a compel data command, {HEAD ~ a function block} of a device publishes {TAIL ~ its output data} on the bus 30 
publishes
Upon receiving a compel data command , { HEAD ~ a function block } of a device publishes { TAIL ~ its output data } on the bus 30
OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH