The buffer element has {HEAD ~ a lateral side} as well as {TAIL ~ a first edge} and a second edge disposed oppositely to each other 
The buffer element has { HEAD ~ a lateral side } as well as { TAIL ~ a first edge } and a second edge disposed oppositely to each other
OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH