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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 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
0. 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.
In addition, mere aggregation of another work not based on the Program with the
Program (or with a work based on the Program) on a volume of a storage or distribution
medium does not bring the other work under the scope of this License.
3. You may copy and distribute the Program (or a work based on it, under Section 2)
in object code or executable form under the terms of Sections 1 and 2 above
provided that you also do one of the following:
a) Accompany it with the complete corresponding machine-readable source
code, which must be distributed under the terms of Sections 1 and 2 above on
a medium customarily used for software interchange; or,
b) Accompany it with a written offer, valid for at least three years, to give any
third party, for a charge no more than your cost of physically performing
source distribution, a complete machine-readable copy of the corresponding
source code, to be distributed under the terms of Sections 1 and 2 above on a
medium customarily used for software interchange; or,
c) Accompany it with the information you received as to the offer to distribute
corresponding source code. (This alternative is allowed only for
noncommercial distribution and only if you received the program in object
code or executable form with such an offer, in accord with Subsection b
above.)
The source code for a work means the preferred form of the work for making
modifications to it. For an executable work, complete source code means all the source
code for all modules it contains, plus any associated interface definition files, plus the
scripts used to control compilation and installation of the executable. However, as a
special exception, the source code distributed need not include anything that is normally
distributed (in either source or binary form) with the major components (compiler,
kernel, and so on) of the operating system on which the executable runs, unless that
component itself accompanies the executable.
If distribution of executable or object code is made by offering access to copy from a
designated place, then offering equivalent access to copy the source code from the same
place counts as distribution of the source code, even though third parties are not
compelled to copy the source along with the object code.
4. You may not copy, modify, sublicense, or distribute the Program except as
expressly provided under this License. Any attempt otherwise to copy, modify,
sublicense or distribute the Program is void, and will automatically terminate
your rights under this License. However, parties who have received copies, or
rights, from you under this License will not have their licenses terminated so long
as such parties remain in full compliance.
5. You are not required to accept this License, since you have not signed it.
However, nothing else grants you permission to modify or distribute the Program
or its derivative works. These actions are prohibited by law if you do not accept
this License. Therefore, by modifying or distributing the Program (or any work
based on the Program), you indicate your acceptance of this License to do so, and
all its terms and conditions for copying, distributing or modifying the Program or
works based on it.
6. Each time you redistribute the Program (or any work based on the Program), the
recipient automatically receives a license from the original licensor to copy,
distribute or modify the Program subject to these terms and conditions. You may
not impose any further restrictions on the recipients’ exercise of the rights granted
herein. You are not responsible for enforcing compliance by third parties to this
License.
7. If, as a consequence of a court judgment or allegation of patent infringement or
for any other reason (not limited to patent issues), conditions are imposed on you
(whether by court order, agreement or otherwise) that contradict the conditions of
this License, they do not excuse you from the conditions of this License. If you
cannot distribute so as to satisfy simultaneously your obligations under this
License and any other pertinent obligations, then as a consequence you may not
distribute the Program at all. For example, if a patent license would not permit
royalty-free redistribution of the Program by all those who receive copies directly
or indirectly through you, then the only way you could satisfy both it and this
License would be to refrain entirely from distribution of the Program.
If any portion of this section is held invalid or unenforceable under any particular
circumstance, the balance of the section is intended to apply and the section as a whole
is intended to apply in other circumstances.
It is not the purpose of this section to induce you to infringe any patents or other
property right claims or to contest validity of any such claims; this section has the sole
purpose of protecting the integrity of the free software distribution system, which is
implemented by public license practices. Many people have made generous
contributions to the wide range of software distributed through that system in reliance
on consistent application of that system; it is up to the author/donor to decide if he or
she is willing to distribute software through any other system and a licensee cannot
impose that choice.
