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Subject: Re: EPD file format....

Author: Dan Newman

Date: 14:14:53 09/23/98

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On September 23, 1998 at 15:53:33, Guillem Barnolas wrote:

>
>Could anyone tell me something about this file format ???... I know it's used to
>store positions for a test, but I don't know anything else..... thanks..
>
>PD: The chess program I'm doing is already playing, but still have to do lots of
>things... I'm preparing it's web page...

You can get a copy of the standard at

ftp://caissa.onenet.net:/pub/chess/PGN/Standard

which has the PGN, SAN, FEN, and EPD standards in it.  (There is
also a separate table of contents file for Standard also in the
PGN directory.)

Briefly, an EPD file has a number of records each of which specifies
a position and may also specify a series of operations.  As
an example, in EPD the opening position (without any operations)
looks like this:

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

There are 4 required fields, the first for piece placement, the
second for side-to-move, the third for castling rights, and the
fourth for EP target square.  Each field is separated from the
next by a single blank.

The piece placement field always has seven slashes (/).  They
separate the strings that represent the placement of the pieces
on each of the eight ranks, starting with the eighth rank and
proceeding in order to the first.  The black pieces are
represented by lower case letters: pnbrqk, and the white by upper
case.  Numbers represent runs of empty squares.

The side to move is given by a lower case 'w' or 'b'.

The castling rights are represented by a string that contains
a 'K' for 'white is allowed to castle on the kingside', a 'Q'
for 'white queenside', and so on.  The letters must always be in
the order KQkq with no spaces.  If there are no castling rights
a '-' sign is used.

The en passant (EP) target square is given by the algebraic
coordinate of the square to which the EP capture would be made.
This field is always filled with a target square if the preceeding
move was a two-square pawn move even if no EP capture can be
made.  (I think that was a mistake myself...)  If there was no
preceeding two-square pawn move, this field is filled with a '-'.

Following the four required fields you can have a series of
operations--the standards document lists a number of these.
The ones I've seen the most are the best-move (bm) operation
and the identifier (id) operation.  I'll just give an example
from the WAC suite:

5rk1/p5pp/8/8/2Pbp3/1P4P1/7P/4RN1K b - - bm Bc3; id "WAC.101";

-Dan.



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