What is a grid reference and how do I use it?
A grid reference is a unique expression comprised of two letters and two groups of numbers, each group consisting of three digits. It is used to identify a specific location, or to give a specific position, when used in conjunction with a suitable Ordnance Survey map. The type of grid reference used to specify a general location is called a six figure grid reference. The worked example that follows uses the North sheet side of the OL28 Ordnance Survey map of the Dartmoor National Park. This map has a scale of 1:25000 making it a very popular map for walkers in the South West. Example grid reference: SX. 664 869. The spacing between elements has been introduced for the sake of clarity only. General information: Notice that the map has a network of blue grid lines forming squares superimposed on it. Observe that the start and finish of each line is numbered on the border margins and at intervals across the map. These numbers that uniquely identify each line are in the range of 0 to 99. O
