                       The XMOD package - version 2.010

This is the README file for the GAP package ``XMOD''.

This package allows for computation with crossed modules;
cat1-groups; morphisms of these structures; 
derivations of crossed modules and the corresponding sections of cat1-groups.
Experimental functions for crossed squares are now included.

Version 1 of ``XMOD'' was accepted for GAP3R4P4 in December 1996.
The first version for GAP4 was XMod 2.001, released in April 2002.
This version, 2.010, is released in October 2007.
A more detailed history is included as Chapter 9 of the manual, 
with minor changes detailed ion the file CHANGES.

The ``XMOD'' package is distributed with the accepted GAP packages.
It may also be obtained from the Bangor ftp pages for
Computational Higher-dimensional Discrete Algebra at:
  http://www.informatics.bangor.ac.uk/public/mathematics/chda/

The XMOD package is Copyright {\copyright} Chris Wensley and Murat Alp, 
1996--2007. 
XMOD 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 2 of the License, or
(at your option) any later version. 
For details, see \URL{http://www.gnu.org/licenses/gpl.html}

============================================================================

Installing `XMod':

1) unpack `xmod.2.010.tar.gz' in the `pkg' subdirectory of the GAP root
   directory.

2) From within GAP load the package with:

gap> LoadPackage("xmod");
true

3) The documentation is in the `doc' subdirectory.

===========================================================================

Chris Wensley and Murat Alp  -  October 2007. 
