Omega Chess Positional Notation (OCPN) is a standard notation for describing a particular board position of a Omega Chess game. The purpose of OCPN is to provide all the necessary information to restart a game from a particular position.
OCPN is based on Forsyth–Edwards Notation (FEN), a system developed by the Scottish newspaper journalist David Forsyth. Forsyth's system became popular in the 19th century; Steven J. Edwards extended it to support use by computers. FEN is an integral part of the Portable Game Notation for chess games, since FEN is used to define initial positions other than the standard one. OCPN does not represent sufficient information to decide on draws by threefold repetition.
Definition
editA OCPN "record" defines a particular game position, all in one text line and using only the ASCII character set. A text file with only OCPN data records should have the file extension ".ocpn".
A OCPN record contains nine fields. The separator between fields is a space. The fields are:
- Piece placement (from white's perspective): The wizard squares and each rank are described, starting with the wizard squares (W1,W2,W3,W4) and then rank 10, ending with rank 1. The contents of each square are described from file a through file h. Following the Standard Algebraic Notation (SAN), each piece is identified by a single letter taken from the standard English names: (Pawn = P, Wizard = W, Champion = C, Rook = R, Knight = N, Bishop = B, Queen = Q, King = K, Fool = F) White pieces are designated using upper-case letters while Black take lowercase. Blank squares are noted using hexadecimal digits 1 through A (the number of blank squares), and "/" separate ranks.
- Active color: "w" means white moves next, "b" means black.
- Castling availability: If neither side can castle, this is "–". Otherwise, this has one or more letters: "K" (White can castle kingside), "Q" (White can castle queenside), "k" (Black can castle kingside), and/or "q" (Black can castle queenside).
- Guarding availability: If neither side can guard, this is "–". Otherwise, this has one or more letters: "K" (White can guard kingside), "Q" (White can guard queenside), "k" (Black can guard kingside), and/or "q" (Black can guard queenside).
- En passant target: If there's no en passant target square, this is "–". If a pawn has just made a 2 or 3-square move, this is the positions "behind" the pawn, separated by /. This is recorded regardless of whether there is a pawn in position to make an en passant capture.
- Fool availability: If neither side may place their fool, this is "-". Otherwise, this has one or more letters: "w" (White may place their fool), "b" (Black may place their fool)
- Fool's Identities: The SAN identification of the last piece each player moved. This is recorded even if there are no fools on the board. If no piece has been moved for a particular player, this is "-"
- Halfmove clock: This is the number of halfmoves since the last pawn advance or capture. This is used to determine if a draw can be claimed under the fifty-move rule.
- Fullmove number: The number of the full move. It starts at 1, and is incremented after Black's move.
Examples
edit- Omega Chess Starting Position:
WWww/crnbqkbnrc/pppppppppp/A/A/A/A/A/A/PPPPPPPPPP/CRNBQKBNRC w KQkq KQkq - wb -- 0 1