Appendix C
♦
Open Source Software Copyright Information
126
CMN-41 Series Installation and Operation Handbook
Copyright © 2009, Harris Corporation
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.
