Copyright (C) 1991, 1999 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.
[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 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.
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