Steps 1 5 are for {TAIL ~ the generation} of {HEAD ~ a special set} [D} of n elements ds 
Steps 1 5 are for { TAIL ~ the generation } of { HEAD ~ a special set } [ D } of n elements ds
OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH