Software License Information for Dante

7
Preamble
The licenses for most software are designed to take away your freedom to share and change it. By
contrast, the GNU General Public Licenses are intended to guarantee your freedom to share and
change free software–to make sure the software is free for all its users.
This license, the Library General Public License, applies to some specially designated Free Software
Foundation software, and to any other libraries whose authors decide to use it. You can use it for your
libraries, too.
When we speak of free software, we are referring to freedom, not price. Our General Public Licenses
are designed to make sure that you have the freedom to distribute copies of free software (and charge
for this service if you wish), that you receive source code or can get it if you want it, that you can
change the software or use pieces of it in new free programs; and that you know you can do these
things.
To protect your rights, we need to make restrictions that forbid anyone to deny you these rights or to
ask you to surrender the rights. These restrictions translate to certain responsibilities for you if you
distribute copies of the library, or if you modify it.
For example, if you distribute copies of the library, whether gratis or for a fee, you must give the reci-
pients all the rights that we gave you. You must make sure that they, too, receive or can get the source
code. If you link a program with the library, you must provide complete object files to the recipients so
that they can relink them with the library, after making changes to the library and recompiling it. And
you must show them these terms so they know their rights.
Our method of protecting your rights has two steps: (1) copyright the library, and (2) offer you this
license which gives you legal permission to copy, distribute and/or modify the library.
Also, for each distributor’s protection, we want to make certain that everyone understands that there
is no warranty for this free library. If the library is modified by someone else and passed on, we want
its recipients to know that what they have is not the original version, so that any problems introduced
by others will not reflect on the original authors’ reputations.
Finally, any free program is threatened constantly by software patents. We wish to avoid the danger
that companies distributing free software will individually obtain patent licenses, thus in effect trans-
forming the program into proprietary software. To prevent this, we have made it clear that any patent
must be licensed for everyone’s free use or not licensed at all.
Most GNU software, including some libraries, is covered by the ordinary GNU General Public License,
which was designed for utility programs. This license, the GNU Library General Public License,
applies to certain designated libraries. This license is quite different from the ordinary one; be sure to
read it in full, and don’t assume that anything in it is the same as in the ordinary license.
The reason we have a separate public license for some libraries is that they blur the distinction we
usually make between modifying or adding to a program and simply using it. Linking a program with
a library, without changing the library, is in some sense simply using the library, and is analogous to
running a utility program or application program. However, in a textual and legal sense, the linked
executable is a combined work, a derivative of the original library, and the ordinary General Public
License treats it as such.
Because of this blurred distinction, using the ordinary General Public License for libraries did not ef-
fectively promote software sharing, because most developers did not use the libraries. We concluded
that weaker conditions might promote sharing better.
However, unrestricted linking of non-free programs would deprive the users of those programs of all
benefit from the free status of the libraries themselves. This Library General Public License is inten-
ded to permit developers of non-free programs to use free libraries, while preserving your freedom as
a user of such programs to change the free libraries that are incorporated in them. (We have not seen
how to achieve this as regards changes in header files, but we have achieved it as regards changes
in the actual functions of the Library.) The hope is that this will lead to faster development of free
libraries.
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, while the latter only works together with the library.
Note that it is possible for a library to be covered by the ordinary General Public License rather than
by this special one.