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, DISTRIBUTI ON 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".)
"Source code" for a work means the preferred form of the work for making
modifications to it. For a library, complete source code means all the source
code for all modules it contains, plus any associated interface definition files,
plus the scripts used to control compilation and installation of the library.
Activities other than copying, distribution and modification are not covered by
this License; they are outside its scope. The act of running a program using the
Library is not restricted, and output from such a program is covered only if its
contents constitute a work based on the Library (independent of the use of the
Library in a tool for writing it). Whether that is true depends on what the
Library does and what the program that uses the Library does.
1. You may copy and distribute verbatim copies of the Library's complete source
code as you receive it, in any medium, provided that you conspicuously and
appropriately publish on each copy an appropriate copyright notice and
disclaimer of warranty; keep intact all the notices that refer to this License and
to the absence of any warranty; and distribute a copy of this License along with
the Library.
You may charge a fee for the physical act of transferring a copy, and you may at
your option offer warranty protection in exchange for a fee.
2. You may modify your copy or copies of the Library or any portion of it, thus
forming a work based on the Library, and copy and distribute such
modifications or work under the terms of Section 1 above, provided that you
also meet all of these conditions:
General Notes
110