Alphanumeric grid

{| class="wikitable" style="text-align:center; width: 20em; height: 20em; float: right;" |- ! !! a !! b !! c !! d !! e !! f |- ! 1 | a1 || b1 || c1 || d1 || e1 || f1 |- ! 2 | a2 || b2 || c2 || d2 || e2 || f2 |- ! 3 | a3 || b3 || c3 || d3 || e3 || f3 |- ! 4 | a4 || b4 || c4 || d4 || e4 || f4 |- ! 5 | a5 || b5 || c5 || d5 || e5 || f5 |- ! 6 | a6 || b6 || c6 || d6 || e6 || f6 |}

thumb|Example of an Alphanumeric board An '''alphanumeric grid''' (also known as '''atlas grid'''<ref>{{cite web |url=http://encyclopedia2.thefreedictionary.com/atlas+grid |title=Atlas grid |website=encyclopedia2.thefreedictionary.com |access-date=2010-03-22}}</ref>) is a simple coordinate system on a grid in which each cell is identified by a combination of a letter and a number.<ref>{{cite web|url=http://support.esri.com/index.cfm?fa%3Dknowledgebase.gisDictionary.search%26search%3Dtrue%26searchTerm%3Dalphanumeric+grid |title=Archived copy |accessdate=2010-03-22 |url-status=dead |archiveurl=https://web.archive.org/web/20071010070525/http://support.esri.com/index.cfm?fa=knowledgebase.gisDictionary.search |archivedate=2007-10-10 }} Retrieved 2010-03-22.</ref>

An advantage over numeric coordinates such as easting and northing, 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; 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 uses an alphanumeric grid to refer to the squares of a chessboard.<ref>http://www.fide.com/fide/handbook?id=125&view=article ''Appendices'' in World Chess Federation Handbook: see part ''C.7'' of section ''C. Algebraic notation''. Retrieved 2010-03-22.</ref>

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

== References ==

Category:Coordinate systems