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.
GNU LESSER GENERAL PUBLIC LICENSE
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 been
distributed under these terms. A "work based on the Library" means either the Library or
any derivative work under copyright law: that is to say, a work containing the Library or a
portion of it, either verbatim or with modifications and/or translated straightforwardly into
