# The GNU General Public License, Version 2, June 1991 (GPLv2)
> Copyright (C) 1989, 1991 Free Software Foundation, Inc. 51 Franklin Street,
> Fifth Floor, Boston, MA 02110-1301, 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 Lesser 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.
This section is intended to make thoroughly clear what is believed to be a
consequence of the rest of this License.
**8.** If the distribution and/or use of the Program is restricted in certain
countries either by patents or by copyrighted interfaces, the original copyright
holder who places the Program under this License may add an explicit
geographical distribution limitation excluding those countries, so that
distribution is permitted only in or among countries not thus excluded. In such
case, this License incorporates the limitation as if written in the body of this
License.
**9.** The Free Software Foundation may publish revised and/or new versions of
the General Public License from time to time. Such new versions will be similar
in spirit to the present version, but may differ in detail to address new
problems or concerns.
Each version is given a distinguishing version number. If the Program specifies
a version number of this License which applies to it and "any later version",
you have the option of following the terms and conditions either of that version
or of any later version published by the Free Software Foundation. If the
Program does not specify a version number of this License, you may choose any
version ever published by the Free Software Foundation.
**10.** If you wish to incorporate parts of the Program into other free programs
whose distribution conditions are different, write to the author to ask for
permission. For software which is copyrighted by the Free Software Foundation,
write to the Free Software Foundation; we sometimes make exceptions for this.
Our decision will be guided by the two goals of preserving the free status of
all derivatives of our free software and of promoting the sharing and reuse of
software generally.
## No Warranty
**11.** BECAUSE THE PROGRAM IS LICENSED FREE OF CHARGE, THERE IS NO WARRANTY FOR
THE PROGRAM, TO THE EXTENT PERMITTED BY APPLICABLE LAW. EXCEPT WHEN OTHERWISE
STATED IN WRITING THE COPYRIGHT HOLDERS AND/OR OTHER PARTIES PROVIDE THE PROGRAM
"AS IS" WITHOUT WARRANTY OF ANY KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING,
BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
PARTICULAR PURPOSE. THE ENTIRE RISK AS TO THE QUALITY AND PERFORMANCE OF THE
PROGRAM IS WITH YOU. SHOULD THE PROGRAM PROVE DEFECTIVE, YOU ASSUME THE COST OF
ALL NECESSARY SERVICING, REPAIR OR CORRECTION.
**12.** IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING
WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MAY MODIFY AND/OR REDISTRIBUTE
THE PROGRAM AS PERMITTED ABOVE, BE LIABLE TO YOU FOR DAMAGES, INCLUDING ANY
GENERAL, SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE USE OR
INABILITY TO USE THE PROGRAM (INCLUDING BUT NOT LIMITED TO LOSS OF DATA OR DATA
BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY YOU OR THIRD PARTIES OR A
FAILURE OF THE PROGRAM TO OPERATE WITH ANY OTHER PROGRAMS), EVEN IF SUCH HOLDER
OR OTHER PARTY HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES.