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".)
"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:
a) The modified work must itself be a software
library.
b) You must cause the files modified to carry
prominent noticesstating 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-
52
