{HEAD ~ A specification} of each block in a first subset is obtained from the library and translated into {TAIL ~ an execution function} of the software implementation of the block 
translated into
{ HEAD ~ A specification } of each block in a first subset is obtained from the library and translated into { TAIL ~ an execution function } of the software implementation of the block
HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH