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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 soft-ware
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.