{TAIL ~ The segmentation} may also define points at which {HEAD ~ aggregate outputs} may be provided, and where checkpoints may be established 
{ TAIL ~ The segmentation } may also define points at which { HEAD ~ aggregate outputs } may be provided , and where checkpoints may be established
TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH