Interface

The position and move format has the following changes and extensions compared to standard FEN and UCI:

one-letter representation for additional piece types

• Cannon = C
• Leopard = L
• Archbishop = A
• Chancellor = M
• Spider = S
• Dragon = D
• Unicorn = U
• Hawk = H
• Elephant = E
• Fortress = F

move format

• The move string for a piece selection (on the first move of the game) is an uppercase letter indicating the piece type, e.g., C for cannon, etc.
• If black chooses to reject white's piece selection, that is denoted by repeating the same piece type. E.g. position startpos moves D D results in the default choice of cannon and leopard.
• A piece placement move is denoted by {piece_type}@{square}, where the square has to be on the 0th or 9th rank, e.g., C@a0 is placing a cannon behind the rook on a1.

FEN format

The starting position has the same FEN string rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1 as in standard chess. Selected and placed pieces are specified in square brackets after the board representation, e.g., for position startpos moves C H C@a0 C@b9 the FEN is rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR[CaH?cbh?] w KQkq - 0 1. The formats for a selected, placed, or already gated piece are:

• H? means that the piece type hawk was selected, but not placed yet by white
• ca means a black cannon was placed on the a-file, i.e., a9. The rank can optionally be specified, e.g., ca9.
• l- means that a black leopard was already gated. This information is required for the engine to know the possible pawn promotion options.

The pieces in brackets can optionally be separated by a slash, e.g., rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR[Ca/H?/cb/h?] w KQkq - 0 1.