The GBR code or Guy-Blandford-Roycroft code is a system of representing the pieces on the board in a chess

Chess

Chess is a two-player board game played on a chessboard, a square-checkered board with 64 squares arranged in an eight-by-eight grid. It is one of the world's most popular games, played by millions of people worldwide at home, in clubs, online, by correspondence, and in tournaments.Each player...

 position. Publications such as EG use it to classify endgame types and to index endgame studies.

In the GBR code, every chess position is represented by six digits, in the following format:

abcd.ef

• a = queens
  Queen (chess)
  The queen is the most powerful piece in the game of chess, able to move any number of squares vertically, horizontally, or diagonally. Each player starts the game with one queen, placed in the middle of the first rank next to the king. With the chessboard oriented correctly, the white queen starts...
  
  
• b = rooks
  Rook (chess)
  A rook is a piece in the strategy board game of chess. Formerly the piece was called the castle, tower, marquess, rector, and comes...
  
  
• c = bishops
  Bishop (chess)
  A bishop is a piece in the board game of chess. Each player begins the game with two bishops. One starts between the king's knight and the king, the other between the queen's knight and the queen...
  
  
• d = knights
  Knight (chess)
  The knight is a piece in the game of chess, representing a knight . It is normally represented by a horse's head and neck. Each player starts with two knights, which begin on the row closest to the player, one square from the corner...
  
  
• e = white pawns
  Pawn (chess)
  The pawn is the most numerous and weakest piece in the game of chess, historically representing infantry, or more particularly armed peasants or pikemen. Each player begins the game with eight pawns, one on each square of the rank immediately in front of the other pieces...
  
  
• f = black pawns

For the first four digits, each white piece counts as 1, and each black piece counts as 3. Thus, for example, if White has two knights and Black has one knight, numeral d = 1 + 1 + 3 = 5. If that is all the material other than the kings, the position is classified 0005. Values 0 through 8 represent all normal permutations of force; 9 is used if either side has promoted

Promotion (chess)

Promotion is a chess rule describing the transformation of a pawn that reaches its eighth rank into the player's choice of a queen, knight, rook, or bishop of the same color . The new piece replaces the pawn on the same square and is part of the move. Promotion is not limited to pieces that have...

 material.

The last two digits of the code represent the number of White and Black pawns, respectively.

Usage

GBR code can be used to refer to a general class of material. For example, the endgame of two knights against pawn (as famously analysed by A.A. Troitzky, leading to his discovery of the Troitzky line), is GBR class 0002.01.

When indexing or referring to specific positions, rather than generalised material imbalances, the code may be extended in various ways. Two common ones are to prefix "+" to indicate the stipulation "White to play and win" or "=" for "White to play and draw"; and to suffix the position of the white and black kings. With these additions, the position to the right, a draw study by Leonid Kubbel

Leonid Kubbel

Leonid Ivanovich Kubbel was a Russian composer of chess endgame studies and problems. He was born in Leningrad at the end of 1891, or beginning of 1892 and died in the same city on April 18, 1942...

 (First Prize, Shakhmaty, 1925), is classified as =0323.12g3g1. (The solution is 1.Bf2+ Kh1 2.h7 c2+ 3.Be3 Rxe3+ 4.Kf2 Rh3 5.Bd5+ cxd5 6.hxg8Q Rh2+ 7.Kf3 c1Q 8.Qg2+ Rxg2). The positions of other pieces can also be added; this produces a notation that provides the same information as Forsyth-Edwards notation

Forsyth-Edwards Notation

Forsyth–Edwards Notation is a standard notation for describing a particular board position of a chess game. The purpose of FEN is to provide all the necessary information to restart a game from a particular position....

.

The code is named after Richard Guy, Hugh Blandford

Hugh Blandford

Hugh Francis Blandford was born in January 1917 in Southampton, England. He was a metallurgist and a chess endgame composer.He spent several years of his childhood in Jamaica with his father, the Reverend Albert Francis Blandford, a Minister in the Congregational church, his mother and two younger...

 and John Roycroft

John Roycroft

Arthur John Roycroft is an English chess endgame study composer and author, who lives in North West London. He is married to Betty Roycroft...

. The first two devised the original system (the Guy-Blandford code) using different figures to represent the number of pieces. Roycroft suggested to count one for a White piece and three for a Black piece in order to make the code easier to memorise.

Examples of GBR code

White material	Black material	GBR class
KQ	K	1000
KR	K	0100
KB	K	0010
KN	K	0001
KNN	K	0002
K	KN	0003
KN	KN	0004
KNN	KN	0005
K	KNN	0006
KN	KNN	0007
KNN	KNN	0008
KNNN	KNN	0009
KPPP	KPP	0000.32
KNN	KP	0002.01
KBB	KN	0023
KQ	KR	1300
KQP	KQ	4000.10
KRP	KR	0400.10
KRRP	KRR	0800.10
KBBP	KNN	0026.10
KBBP	KRNPP	0323.12