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GNU LESSER GENERAL PUBLIC LICENSE
Version 2.1, February 1999
Copyright (C) 1991, 1999 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.
[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 version
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 Software
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 referring to freedom of use, 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 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 restrictions that forbid distributors
to deny you these rights or to ask you to surrender these rights. These
restrictions translate to certain responsibilities for you if you distribute
copies of the library or if you modify it.
For example, if you distribute copies of the library, whether gratis or for a
fee, you must give the recipients all the rights that we gave you. You must
make sure that they, too, receive or can get the source code. If you link
other code with the library, you must provide complete 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 then
library, and (2) we offer you this license, which gives you legal permission
to copy, distribute and/or modify the library.
To protect each distributor, we want to make it very clear that there is no
warranty for the free library. Also, if the library is modified by someone
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. Therefore, 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 ordinary 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 therefore permits such linking only if the entire combination fits its
criteria of freedom. The Lesser General Public License permits more lax
criteria 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 competing 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 programs 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 free library to free software only, so we use the Lesser General
Public License.
In other cases, permission to use a particular library in non-free programs
enables a greater number of people to use a large body of free software.
For example, permission to use the GNU C Library in non-free programs
enables many more people to use the whole GNU operating system, as
well as its variant, the GNU/Linux operating system.
Although the Lesser General Public License is Less protective of the
users' freedom, it does ensure that the user of a program that is linked
with the Library has the freedom and the wherewithal to run that program
using a modified version of the Library.
The precise terms and conditions for copying, distribution and modification
follow. Pay close attention to the difference between a "work based on the
library" and a "work that uses the library". The former contains code
derived from the library, whereas the latter must be combined with the
library in order to run.
TERMS AND CONDITIONS FOR COPYING, DISTRIBUTION
AND MODIFICATION
0. This License Agreement applies to any software library or other
program which contains a notice placed by the copyright holder or other
authorized party saying it may be distributed under the terms of this
Lesser General Public License (also called "this License"). Each licensee
is addressed as "you".
A "library" means a collection of software functions and/or data prepared
so as to be conveniently linked with application programs (which use
some of those functions and data) to form executables.
The "Library", below, refers to any such software library or work which has