{HEAD ~ A cumulative threat risk value} for {TAIL ~ each} of the grid cells is calculated, and an allowable threat risk per grid cell is established based on a rule set 
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{ HEAD ~ A cumulative threat risk value } for { TAIL ~ each } of the grid cells is calculated , and an allowable threat risk per grid cell is established based on a rule set
HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH