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