The Forsyth Edward notation (FEN) or in the extended form (X-FEN) is a short notation, with which any board position in chess can be written down.

Structure

The FEN is divided in 6 groups, which are separate by blanks:

The basic position (1. Example) of the chessboard in FEN:

rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1 

1. Group

The 1. Group describes the positions of the figures on the board. Possible indications are:

1 2 3 4 5 6 7 8 p r n. b. q k P R N.B.Q K/ 

Begun with the 8. up to the 1. Row by the dozen, separately by a diagonal stroke "“/"”, the positions of the figures on the board are indicated. White figures are indicated in large, black figures in small letters. For the figures the abbreviations of the English designations are used (r=Rook, n=Knight, b=Bishop q=Queen, k=King, p=Pawn). The number of empty fields is represented as number.

2. Example: A white king on e4 a black king on c5 results in the following 1. Group:

8/8/8/2k5/4K3/8/8/8  

2. Group

The 2. Group indicates attractive players. Possible character strings are (in EBNF):

"“w"” | "“b"” 

• w = white
• b = black

3. Group

3. Group indicates the still permitted castlings. Possible character strings are:

"“K"” ["“Q"”] ["“k"”] ["“q"”] | ["“K"”] Q ["“k"”] ["“q"”] | ["“K"”] ["“Q"”] k ["“q"”] | ["“K"”] ["“Q"”] ["“k"”] q |"” - "“ 

• K = white can rochieren briefly
• Q = white can rochieren long
• k = black can rochieren briefly
• q = black can rochieren long
• - = castling on no side possible

With the indication of the indications the large letters are to be set absolutely before the small. The letter "“K"” before the letter "“Q"” and "“k"” before "“q"”.

4. Group

The 4. Group indicates a possible "“EN passant"” - to course. Possible character strings are:

"“-"” | (("“A " | " b " | " C " | " D " | " e " | " f " | " g " | " h"”) ("“3 " | " 6"”)) 

If in the last course a farmer advanced two fields, the jumped over field is indicated, independently of whether "„a EN-passant "“impact is possible on this field or not. Otherwise "“-"” one indicates.

Example: after farmer f2-f4 becomes in the FEN in the 4. Group of "“f3"” indicated.

5. and 6. Group

In the 5. Group is indicated the number of the sections since the last farmer course and/or striking a figure. This value is to be supervised importantly around the

In the 6. Group is indicated the number of the next course. In the starting position the value is 1. After each course of black by the value 1 one increases.

Possible character string are here positive whole numbers.

X-FEN (FEN extended)

To the representation of all conceivable positions in the Chess960 (8x8-Brett) or Capablanca random Chess (10x8 - board) ((carriage return character)) the classical FEN is not sufficient. Therefore for this a downward-compatible extension of the conventional FEN is inevitable. That means: All positions, which are codable by means of FEN so far already, must be coded by an extension in 100% an identical form. Of pure hard the Scharnagl 2003 introduced X-FEN carries this out. And X-FEN (before times FRC-FEN) is proven for years.

Portions are represented in the PGN format (portable Game notation). With exception of conventional games of chess must be taken up with a storage by Chess960 or (carriage return character) portions (Capablanca random Chess) also the respective Startstellungen with. That takes place by definition with traditional games of chess by means of set UP tags and a FEN stringer, with Chess960 and (carriage return character) portions thus in compatible way over a X-FEN-stringer.

Definition

Basis of the X-FEN is the conventional FEN. It differs only in the kind, like castling tags and e.p. - Day to be used. In addition it supports 10x8 positions, which are based to extended figure set (additional figures chancellors and archbishop) on Jose Raul Capablancas.

EN-passant coding

For the improvement of the clarity an indication is one e.p. - Coordinate only permissible if the farmer concerned stands directly beside an opposing farmer platziert and e.p. - Field is empty.

Castling rights coding

It from the FEN admitted castling tags "“KQkq"” used. As usual small letters mean black castling rights and large letters white castling rights. "“Kk"” identify an ability to the g-castling (and/or i-castling with the 10x8 chess), to "“Qq"” that one to the C-castling. Again and quintessential point of the regulation is that such granted castling rights are assigned to the side concerned normally at the furthest outside standing own tower. However deviating from it if an internal tower should possess the castling right, then exclusively in these cases conventional castling day by the column letter of the tower concerned one replaces, with white by means of capital letters.

The castling goal of the king is usual either two fields of the left (white) edge, or a field of the right edge removes. There are however also variants with symmetrically distributed target fields (e.g. Janusschach), both per a field from the edge far away. Then the castling block a "“s"” is placed in front. Another prefix "“m"” means: modern castling (e.g. Embassy Chess or Chess480). Here the king draws a normal castling distance (8x8: 2 steps, 10x8: 3 steps) to the side, maximally however to direct before the edge.

10x8 chess

Ten sequential free fields in a row are coded with "“10"”, nine with "“9"”. The archbishop (Springer + runners) receives the letter "“A"” (English A rchbishop), chancellor (Springer + tower) gets "“C"” (English Chancellor). Black figures are symbolized here in used way with small letters. 10x8-Beispiel: Capablanca random Chess

Compatibility

The Startstellung of traditional chess and all 18 pseudo FRC positions (castlingable towers and kings stand on their traditional places) code themselves beyond that including the subsequent positions resulting in from it by X-FEN perfectly identically as before. Thus X-FEN is fully downward compatible to the conventional FEN.

Filtering of portions

If one should want to consider only classical games of chess from a PGN file (a problem already existing with the Shuffle Chess), then is to be paid attention only to select however only such PGN entries without existing FEN day.

Example

Castling right internal tower before 11. O-O

X-FEN:

rn2k1r1/ppp1pp1p/3p2p1/5bn1/P7/2N2B2/1PPPPP2/2BNK1RR w Gkq - 4 11 

PGN:

[Event "“SmirfGUI Computerchess Game"”] [Site "“CHESSBOX"”] [DATE "“2005.06.19"”] [Time "“10: 22: 29"”] [Round "“test"”] [White "“White"”] [Black "“Black"”] [Result "“*"”] [Annotator "“R. Scharnagl"”] [SetUp "“1"”]

[FEN "“rnbnkqrb/pppppppp/8/8/8/8/PPPPPPPP/RNBNKQRB w KQkq - 0 1"”]

1. h4 g6 2. g3 Bf6 3. a4 Qh6 4. Ra3 Bxh4 5. gxh4 Qxh4 6. Qh3 Qxh3 7. Rxh3 Ne6 8. Bf3 d6 9. Nbc3 Ng5 10. Rhh1 Bf5 11. O-O * 

See also

• Chess program
• Computer chess
• Portable Game notation
• GBR code
• XBoard minutes
• Universal Chess interface (UCI)

Related links

• Pure hard Scharnagls ChessBox (German/English)

Articles in category "Forsyth Edward notation"

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