Users Guide

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.
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 another language. (Hereinafter, translation is included without limitation in
the term "modification".)