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