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The GNU General Public License (GPL)
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.
TERMS AND CONDITIONS FOR COPYING, DISTRIBUTION AND MODIFICATION
This License applies to any program or other work which contains a notice placed by the copyright holder saying it may be
distributed under the terms of this General Public License. The "Program", below, refers to any such program or work, and a
"work based on the Program" means either the Program or any derivative work under copyright law: that is to say, a work
containing the Program or a portion of it, either verbatim or with modifications and/or translated into another language.
(Hereinafter, translation is included without limitation in the term "modification".) Each licensee is addressed as "you".
Activities other than copying, distribution and modification are not covered by this License; they are outside its scope. The act of
running the Program is not restricted, and the output from the Program is covered only if its contents constitute a work based on
the Program (independent of having been made by running the Program). Whether that is true depends on what the Program
does.
(1) You may copy and distribute verbatim copies of the Program's source code as you receive it, in any medium, provided that
you conspicuously and appropriately publish on each copy an appropriate copyright notice and disclaimer of warranty; keep
intact all the notices that refer to this License and to the absence of any warranty; and give any other recipients of the
Program a copy of this License along with the Program.
You may charge a fee for the physical act of transferring a copy, and you may at your option offer warranty protection in
exchange for a fee.
(2) You may modify your copy or copies of the Program or any portion of it, thus forming a work based on the Program, and
copy and distribute such modifications or work under the terms of Section 1 above, provided that you also meet all of these
conditions:
a) You must cause the modified files to carry prominent notices stating that you changed the files and the date of any
change.
b) You must cause any work that you distribute or publish, that in whole or in part contains or is derived from the Program
or any part thereof, to be licensed as a whole at no charge to all third parties under the terms of this License.
c) If the modified program normally reads commands interactively when run, you must cause it, when started running for
such interactive use in the most ordinary way, to print or display an announcement including an appropriate copyright
notice and a notice that there is no warranty (or else, saying that you provide a warranty) and that users may
redistribute the program under these conditions, and telling the user how to view a copy of this License. (Exception: if
the Program itself is interactive but does not normally print such an announcement, your work based on the Program
is not required to print an announcement.)
These requirements apply to the modified work as a whole. If identifiable sections of that work are not derived from the
Program, and can be reasonably considered independent and separate works in themselves, then this License, and its
terms, do not apply to those sections when you distribute them as separate works. But when you distribute the same
sections as part of a whole which is a work based on the Program, the distribution of the whole must be on the terms of this
License, whose permissions for other licensees extend to the entire whole, and thus to each and every part regardless of
who wrote it.
Thus, it is not the intent of this section to claim rights or contest your rights to work written entirely by you; rather, the intent
is to exercise the right to control the distribution of derivative or collective works based on the Program.
