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
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