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[This is the fi rst 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 fi rst 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 fi les 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 modifi ed 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 specifi ed 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 fi ts 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 modifi ed version of the Library.
The precise terms and conditions for copying,