The method 1, wherein providing the database comprises associating the map objects with respective data layers, and wherein identifying the two or more matched map objects comprises searching for {HEAD ~ the two or more matched map objects} only within {TAIL ~ a subset} of the data layers 
The method 1 , wherein providing the database comprises associating the map objects with respective data layers , and wherein identifying the two or more matched map objects comprises searching for { HEAD ~ the two or more matched map objects } only within { TAIL ~ a subset } of the data layers
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH