GNU LESSER GENERAL PUBLIC LICENSE
Version 2.1, February 1999
Copyright (C) 1991, 1999 Free Software Foundation, Inc.
51 Franklin St, 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.
[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 the 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
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