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.
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".)
"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.
"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.
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: 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 any
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.)
These requirements apply to the modified work as a whole. If
identifiable sections of that work are not derived from the
Library, and can be reasonably considered independent and
separate works in themselves, then this License, and its terms,
do not apply to those sections when you distribute them as
separate works. But when you distribute the same sections as
part of a whole which is a work based on the Library, the
distribution of the whole must be on the terms of this License,
whose permissions for other licensees extend to the entire
whole, and thus to each and every part regardless of who wrote
it.
Thus, it is not the intent of this section to claim rights or contest
your rights to work written entirely by you; rather, the intent is
to exercise the right to control the distribution of derivative or
collective works based on the Library.
59
