Portable Game Notation

PGN was devised around 1993, by Steven J. Edwards, and was first popularized and specified[1] via the Usenet newsgroup rec.games.chess.

There are no special control codes involving escape characters, or carriage returns, and linefeeds to separate the fields, and superfluous embedded spaces are usually skipped when parsing.

SAN kingside castling is indicated by the sequence O-O; queenside castling is indicated by the sequence O-O-O (note that these are capital Os, not zeroes, contrary to the FIDE standard for notation).

An annotator who wishes to suggest alternative moves to those actually played in the game may insert variations enclosed in parentheses.

Here is the PGN format of the 29th game of the 1992 match played in Yugoslavia between Bobby Fischer and Boris Spassky: Many chess variants can be recorded using PGN, provided the names of the pieces can be limited to one character, usually a letter and not a number.

NAGs were first formally documented in 1994 by Steven J. Edwards in his "Portable Game Notation Specification and Implementation Guide".

[5] Within the PGN specification, 256 NAGs are proposed of which the first 140 are defined; the remainder were reserved for future definition.

The objective was to devise an alternative representation of these symbols which could be incorporated in the simple computer file format proposed as the PGN standard.

This mechanism allowed often sophisticated typography to be expressed using the simple ASCII character set.

Since its inception there has been no attempt to further formalise or standardise the meaning of the undefined 116 NAGs although PGN editors, such as ChessPad, have variously used these higher glyphs.