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.
All manuals and user guides at all-guides.com
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:
Eng-14
a) The modified work must itself be a software library.
b) You must cause the files modified to carry prominent notices
stating that you changed the files and the date of an change.
c) You must cause the whole of the work to be licensed at no charge
to all third parties under the terms of this License.
d) If a facility in the modified Library refers to a function or a table of
data to be supplied by an application program that uses the facility,
other than as an argument passed when the facility is invoked, then
you must make a good faith effort to ensure that, in the event an
application does not supply such function or table, the facility still
operates, and performs whatever part of its purpose remains
meaningful.
(For example, a function in a library to compute square roots has a
purpose that is entirely well-defined independent of the application.
Therefore, Subsection 2d requires that any application-supplied
function or table used by this function must be optional: if the
application does not supply it, the square root function must still
compute square roots.)