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