, a form of notation
very similar to algebraic notation
, but comprised solely of numbers.
It is used mainly in correspondence chess, where the two players may not speak the same language, or even have the same alphabet. Increasingly, "International Notation" is used to refer to the internationally-accepted algebraic notation, and so this numeric notation can be called "International Numeric Notation" or "Correspondence Chess Notation".
Both ranks and columns are numbered, and the start and end coordinates of each move are given. Hence, 1. e4 e5 becomes 1. 5254 5755. These 4-digit codes are sufficent to describe almost all possible moves in chess. Castling is described by the king's move only. Checks, captures, and other commentaries are not notated.
For pawn promotion, a fifth digit is added to the end of the usual four, representing the piece chosen by the player. A Queen is 1, Rook is 2, 3 is Bishop and 4 is Knight.