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.
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
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
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
The precise terms and conditions for copying, distribution
and modification follow.