Chess notation systems are used to record either the moves made or the position of the pieces in a game of chess. Chess notation is used in chess literature, and by players keeping a record of an ongoing game. The earliest systems of notation used lengthy narratives to describe each move; these gradually evolved into more compact notation systems. Algebraic notation is now the accepted international standard, with several variants. Descriptive chess notation was used in English- and Spanish-language literature until the late 20th century, but is now obsolescent. Portable Game Notation (PGN) is a text file format based on English algebraic notation which can be processed by most chess software. Other notation systems include ICCF numeric notation, used for international correspondence chess, and systems for transmission using Morse code over telegraph or radio. The standard system for recording chess positions is Forsyth–Edwards Notation (FEN). Notation systems In organized competition, both players are required to keep a record of the moves played on a . If required, score sheets may be used to resolve disputes, for example about whether an illegal move has been made or whether a threefold repetition has occurred. In addition, if the time control requires the players to complete a specified number of moves in a specified time, an accurate count of the moves must be kept. All chess coaches strongly recommend the recording of one's games so that one can look for improvements in one's play. Algebraic notation is the most widely used method for recording moves. It is based on a system of co-ordinates (a–h for files, 1–8 for ranks) to uniquely identify each square. In embryonic form it was used by Philip Stamma in the 1737 book Essai sur le jeu des echecs. It was later adopted (in long form) by the influential Handbuch des Schachspiels and became standard in German publications. It is more compact and less prone to error than the English descriptive system. Algebraic notation is the official notation of FIDE; if a player records the game in a different notation system, their scoresheet may not be used as evidence in the event of a dispute. The U.S. Chess Federation prefers the use of algebraic notation but still permits descriptive notation. Long algebraic notation includes the starting and of the piece. Short algebraic notation omits the starting and of the piece, unless it is necessary to disambiguate the move. Minimal