
    Program: extract -- a Portable Game Notation (PGN) extractor.
    Copyright (C) 1994 David Barnes
    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation; either version 1, or (at your option)
    any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program; if not, write to the Free Software
    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.

    David Barnes may be contacted as D.J.Barnes@ukc.ac.uk



Extract.zip
===========
extract.zip contains a program to extract selected games from a
PGN format data file. The extract.zip file contains:

    A README describing how the program is used.
    A DOS executable.
    ANSI C source for compilation under UNIX or DOS.
    UNIX and DOS makefiles.

Overview
========
There are several ways to specify the criteria on which to extract:
textual move sequences, positions reached after a sequence of moves,
and information in the tag fields. Extract allows you to do all of
these.  As well as lexical and syntactic analysis of game files the
program includes a semantic analyser which will report errors in game
scores.

This version is significantly different from previous releases in the
inclusion of semantic analysis of games.  It also introduces the
facility to search for games based on the position reached at the end
of a move sequence (a positional variation) as opposed to simply a
textual sequence of moves (a textual variation).  There is also an
option to attempt to detect duplicate games.  Extracted games may be
written out to either include or exclude comments, NAGs, and variations.

Games to be extracted are specified by listing opening lines of
interest and/or extraction criteria based upon the information in the
tag fields of a game.  It is possible to specify notational
alternatives for moves and to have the moves of variations tried in
different permutations in an effort to detect transpositions.
Don't-care moves of a variation may also be specified.

For more information, see the full README file in extract.zip.

David Barnes (D.J.Barnes@ukc.ac.uk)
