Chess notation is the term for several systems that have developed to record either the moves made in a game of chess or the position of pieces on a chessboard. The earliest systems of notation used lengthy narratives to describe each move; these gradually evolved into terser notation systems. Currently algebraic chess notation is the accepted standard and is widely used. Algebraic notation has several variations. Descriptive chess notation was used in English- and Spanish-language literature until the late 20th century, but is now obsolete. There are some special systems for international correspondence chess. Portable Game Notation is used when working with computer chess programs. Systems also exist for transmission using Morse code over telegraph or radio.