Title: Grid reference system - Wikipedia
Headings: Grid reference system
Grid reference system
Contents
Grid coordinates
Notation and conventions
Grid north
Types
See also
References

Content: Types
Grid systems vary, but the most common is a square grid with grid lines intersecting each other at right angles and numbered sequentially from the origin at the bottom left of the map. The grid numbers on the east-west (horizontal) axis are called Eastings, and the grid numbers on the north-south (vertical) axis are called Northings. Numerical grid references consist of an even number of digits. Eastings are written before Northings. Thus in a 6 digit grid reference 123456, the Easting component is 123 and the Northing component is 456, i.e. if the smallest unit is 100 metres, it refers to a point 12.3 km east and 45.6 km north from the origin. Grids may be arbitrary, or can be based on specific distances, for example some maps use a one-kilometre square grid spacing. A grid reference locates a unique square region on the map. The precision of location varies, for example a simple town plan view may use a simple alphanumeric grid system with single letters for Eastings and single numbers for Northings. A grid reference in this system, such as 'H3', locates a particular square rather than a single point. Points can be located by grid references on maps that use a standard system for Eastings and Northings, such as the Universal Transverse Mercator used worldwide, or the Ordnance Survey National Grid used by Ordnance Survey in the UK.