FEN is a common extension for a text file which contains six specific data records which represent a single position in a game of chess. Short for Forsythe-Edwards Notation, the file is best used for resuming a physical game which was interrupted. *.FEN files interact well with PGN software and chess engines, and are practically a requirement for some chess variants – such as Fischer Random – which have non-standard starting squares for the pieces.
Data Elements in a FEN file are separated by a space. The board definition is populated from File A to H, one Rank at a time, beginning with 8 and working down the board to 1. The black pieces are represented by lowercase letters; the white by uppercase. Empty squares are represented by a number, indicating consecutive empty squares from left to right.
The starting position of a standard game of chess is represented in FEN as:
rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR W KQkq – 0 1
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After opening move 1.e4, the FEN representation would be:
rnbqkbnr/pppppppp/8/8/4p3/8/PPPP1PPP/RNBQKBNR B KQkq e3 0 1
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If the game continued 1… Nf6 2.Nc3 c5 the FEN representation would be:
rnbqkb1r/pp1ppppp/5n2/2p5/4p3/2N5/PPPP1PPP/RNBQKBNR B KQkq c2 0 3
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And the board itself would look like:
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♟ |
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♙ |
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♙ |
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♘ |
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1 - Wikipedia. "Forsythe-Edwards Notation". Accessed 7/31/2019.
BQ-08-273