Once the minimum number of {HEAD ~ index entries} is determined {TAIL ~ a grid} can be partitioned into the appropriate number of grid cells to support efficient grid indexing 
Once the minimum number of { HEAD ~ index entries } is determined { TAIL ~ a grid } can be partitioned into the appropriate number of grid cells to support efficient grid indexing
OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH