These can be in parallel or in sequence, and a set of parallel modules can also be in {HEAD ~ sequence} with {TAIL ~ a subsequent set} of parallel modules 
with
These can be in parallel or in sequence , and a set of parallel modules can also be in { HEAD ~ sequence } with { TAIL ~ a subsequent set } of parallel modules
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH