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