Ordnance Survey National Grid
The system can also be used to give the location of a smaller area inside a lettered square. This is done by giving the distance east and north from the southwest corner of the square. For example, NH0325 (or NH 03 25) means a one-kilometre square whose southwest corner is 3 km east and 25 km north from the southwest corner of square NH. The system can also specify areas smaller than one kilometre. For example, the grid reference of the 100-metre square containing the summit of Ben Nevis is .