Thus, each block may have {TAIL ~ a single specification} in block specifications 504 that may be used to generate either a software or hardware implementation of {HEAD ~ the block} 
Thus , each block may have { TAIL ~ a single specification } in block specifications 504 that may be used to generate either a software or hardware implementation of { HEAD ~ the block }
OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD