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

File:Xadrez-not_algebrica_bluewhite.png

An alphanumeric grid (also known as atlas grid{{cite web |url=http://encyclopedia2.thefreedictionary.com/atlas+grid |title=Atlas grid |website=encyclopedia2.thefreedictionary.com |access-date=2010-03-22}}) is a simple coordinate system on a grid in which each cell is identified by a combination of a letter and a number.{{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.

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.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.

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