GNU GENERAL PUBLIC LICENSE
Version 2, June 1991
Copyright (C) 1989, 1991 Free Software Foundation, Inc.
59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
Everyone is permitted to copy and distribute verbatim copies
of this license document, but changing it is not allowed.
Preamble
The licenses for most software are designed to take away your freedom to share and change it.
By contrast, the GNU General Public License is intended to guarantee your freedom to share
and change free software--to make sure the software is free for all its users. This General
Public License applies to most of the Free Software Foundation's software and to any other
program whose authors commit to using it. (Some other Free Software Foundation software is
covered by the GNU Library General Public License instead.) You can apply it to your
programs, too.
When we speak of free software, we are referring to freedom, not price. Our General Public
Licenses are designed to make sure that you have the freedom to distribute copies of free
software (and charge for this service if you wish), that you receive source code or can get it if
you want it, that you can change the software or use pieces of it in new free programs; and that
you know you can do these things.
To protect your rights, we need to make restrictions that forbid anyone to deny you these rights
or to ask you to surrender the rights. These restrictions translate to certain responsibilities for
you if you distribute copies of the software, or if you modify it.
For example, if you distribute copies of such a program, whether gratis or for a fee, you must
give the recipients all the rights that you have. You must make sure that they, too, receive or
can get the source code. And you must show them these terms so they know their rights.
We protect your rights with two steps: (1) copyright the software, and (2) offer you this license
which gives you legal permission to copy, distribute and/or modify the software.
Also, for each author's protection and ours, we want to make certain that everyone
understands that there is no warranty for this free software. If the software is modified by
someone else and passed on, we want its recipients to know that what they have is not the
original, so that any problems introduced by others will not reflect on the original authors'
reputations.
Finally, any free program is threatened constantly by software patents. We wish to avoid the
danger that redistributors of a free program will individually obtain patent licenses, in effect
making the program proprietary. To prevent this, we have made it clear that any patent must be
licensed for everyone's free use or not licensed at all.
The precise terms and conditions for copying, distribution and modification follow.
