{HEAD ~ a second escapement} and {TAIL ~ a second code reader} associated with said second queuing station; and 
{ HEAD ~ a second escapement } and { TAIL ~ a second code reader } associated with said second queuing station ; and
HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH