GNU LESSER GENERAL PUBLIC
LICENSE
Version 2.1, February 1999
Copyright (C) 1991, 1999 Free Software Foun-
dation, Inc., 59 Temple Place, Suite 330, Bos-
ton, MA 02111-1307 USA
Everyone is permitted to copy and distribute
verbatim copies of this license document, but
changing it is not allowed.
[This is the first released version of the Lesser
GPL. It also counts as the successor of the GNU
Library Public License, version 2, hence the ver-
sion number 2.1.]
Preamble
The licenses for most software are designed to
take away your freedom to share and change it.
By contrast, the GNU General Public Licenses
are intended to guarantee your freedom to
share and change free software--to make sure
the software is free for all its users.
This license, the Lesser General Public License,
applies to some specially designated software
packages--typically libraries--of the Free Soft-
ware Foundation and other authors who decide
to use it. You can use it too, but we suggest you
first think carefully about whether this license
or the ordinary General Public License is the
better strategy to use in any particular case,
based on the explanations below.
When we speak of free software, we are refer-
ring to freedom of use, not price. Our General
Public Licenses are designed to make sure that
you have the freedom to distribute copies of
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if you want it; that you can change the software
and use pieces of it in new free programs; and
that you are informed that you can do these
things.
To protect your rights, we need to make restric-
tions that forbid distributors to deny you these
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These restrictions translate to certain responsi-
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For example, if you distribute copies of the
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give the recipients all the rights that we gave
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or can get the source code. If you link other
code with the library, you must provide com-
plete object files to the recipients, so that they
can relink them with the library after making
changes to the library and recompiling it. And
you must show them these terms so they know
their rights.
We protect your rights with a two-step method:
(1) we copyright the library, and (2) we offer
you this license, which gives you legal permis-
sion to copy, distribute and/or modify the
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To protect each distributor, we want to make it
very clear that there is no warranty for the free
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one else and passed on, the recipients should
know that what they have is not the original
version, so that the original author's reputation
will not be affected by problems that might be
introduced by others.
Finally, software patents pose a constant threat
to the existence of any free program. We wish
to make sure that a company cannot effectively
restrict the users of a free program by obtaining
a restrictive license from a patent holder. There-
fore, we insist that any patent license obtained
for a version of the library must be consistent
with the full freedom of use specified in this
license.
Most GNU software, including some libraries, is
covered by the ordinary GNU General Public
License. This license, the GNU Lesser General
Public License, applies to certain designated
libraries, and is quite different from the ordi-
nary General Public License. We use this license
for certain libraries in order to permit linking
those libraries into non-free programs.
When a program is linked with a library,
whether statically or using a shared library, the
combination of the two is legally speaking a
combined work, a derivative of the original
library. The ordinary General Public License the-
refore permits such linking only if the entire
combination fits its criteria of freedom. The Les-
ser General Public License permits more lax cri-
teria for linking other code with the library.
We call this license the "Lesser" General Public
License because it does Less to protect the
user's freedom than the ordinary General Public
License. It also provides other free software
developers Less of an advantage over compe-
ting non-free programs. These disadvantages
are the reason we use the ordinary General
Public License for many libraries. However, the
Lesser license provides advantages in certain
special circumstances.
For example, on rare occasions, there may be a
special need to encourage the widest possible
use of a certain library, so that it becomes a de-
facto standard. To achieve this, non-free pro-
grams must be allowed to use the library. A
more frequent case is that a free library does
the same job as widely used non-free libraries.
In this case, there is little to gain by limiting the
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