{TAIL ~ A dataset} including data elements and order keys for indicating {HEAD ~ an ordering} of the data elements is stored 
{ TAIL ~ A dataset } including data elements and order keys for indicating { HEAD ~ an ordering } of the data elements is stored
TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH