GBR code

GBR takes its initials from Guy, Blandford, and Roycroft. It is used mainly to classify endgame studies and endings by their set of pieces. Its basic form has four digits and, when pawns are included, two further digits after a point.

How it is built

1. The four digits before the point follow Q, R, B, N order: queen, rook, bishop, and knight.
2. For each piece type, add 1 for every White piece and 3 for every Black piece. Dividing the digit by 3 then gives the Black count as quotient and the White count as remainder.
3. After the point, the first digit counts White pawns and the second counts Black pawns. Kings are omitted because an ordinary position contains one of each color.

The example 0002.01 means no queens, rooks, or bishops; two White knights; no White pawns; and one Black pawn. The code describes material, not the side to move, the result, or the squares.

That separates it from Forsyth notation, which locates pieces on the board. Extended GBR schemes can append squares and other data, but the basic material code remains a classification of force.