An alphanumeric grid (also known as atlas grid) is a simple

coordinate system In geometry, a coordinate system is a system that uses one or more numbers, or coordinates, to uniquely determine the position of the points or other geometric elements on a manifold such as Euclidean space. The order of the coordinates is sig ...

on a

grid Grid, The Grid, or GRID may refer to: Common usage * Cattle grid or stock grid, a type of obstacle is used to prevent livestock from crossing the road * Grid reference, used to define a location on a map Arts, entertainment, and media * News g ...

in which each cell is identified by a combination of a letter and a number. An advantage over numeric coordinates such as

easting and northing A projected coordinate system, also known as a projected coordinate reference system, a planar coordinate system, or grid reference system, is a type of spatial reference system that represents locations on the Earth using cartesian coordina ...

, which use two numbers instead of a number and a letter to refer to a grid cell, is that there can be no confusion over which coordinate refers to which direction. As an easy example, one could think about

battleship A battleship is a large armored warship with a main battery consisting of large caliber guns. It dominated naval warfare in the late 19th and early 20th centuries. The term ''battleship'' came into use in the late 1880s to describe a type of ...

; simply match the number at the top to the number on the bottom, then follow the two lines until they meet in a spot.

Algebraic chess notation Algebraic notation (or AN) is the standard method for recording and describing the moves in a game of chess. It is based on a system of coordinates to uniquely identify each square on the chessboard. It is used by most books, magazines, and newsp ...

uses an alphanumeric grid to refer to the squares of a

chessboard A chessboard is a used to play chess. It consists of 64 squares, 8 rows by 8 columns, on which the chess pieces are placed. It is square in shape and uses two colours of squares, one light and one dark, in a chequered pattern. During play, the bo ...

.http://www.fide.com/fide/handbook?id=125&view=article ''Appendices'' in

World Chess Federation The International Chess Federation or World Chess Federation, commonly referred to by its French acronym FIDE ( Fédération Internationale des Échecs), is an international organization based in Switzerland that connects the various national c ...

Handbook: see part ''C.7'' of section ''C. Algebraic notation''. Retrieved 2010-03-22. Some kinds of

geocode A geocode is a code that represents a geographic entity (location or object). It is a unique identifier of the entity, to distinguish it from others in a finite set of geographic entities. In general the ''geocode'' is a human-readable and ...

also use letters and numbers, typically several of each in order to specify many more locations over much larger regions.

References

Coordinate systems