ThresholdsData
           SingleThresholdData (0,0,0)
                FieldThreshInstance
                  FieldThreshCompare field0
		      fieldname
		      threshold tile0
		      threshold tile1
		      threshold tile2...
                  FieldThreshCompare field1

                  FieldThreshCompare field2

           SingleThresholdsData (0,0,1)



           SingleThresholdsData (n0,n1,n2)