gnulib/doc/Copyright/conditions.text

Legal Issues about Contributing Code to GNU	last updated 14 July 2015

Project GNU has to be careful to obey copyright laws, even though
these laws are wrong when they stop people from sharing generally
useful published information such as software, because we are in the
public eye.  We also use copyright to defend users' freedom, by means
of copyleft (though this does not excuse copyright law for helping
to make software proprietary).

This means that if you want to contribute software to GNU, you have to
do something to give us legal permission to use it.  There are three
ways this can be done:

* Assign the copyright to the Free Software Foundation.
This allows the FSF to act to stop violations of the GPL.

* Keep the copyright and release the program yourself under the GNU
GPL.  (This alternative is too impractical for contributions to a
preexisting FSF-copyrighted GNU program.)

* Put the code in the public domain.  Then there is nothing to stop
hoarding of modified versions, but we can still use the program in GNU.

Most of these alternatives require a signed piece of paper, or in some
cases a digital signature, to make it happen.

* Assigning copyright.

Assigning the copyright means signing a contract that makes the Free
Software Foundation the "owner" of the program according to the law.
As the copyright holder, the Foundation can sue anyone who tries to
distribute the program as a proprietary product.  We are willing to
keep your name on the program as the author for as long as the program
remains recognizably distinct.  ("Owner" is in quotes to show that we
don't really believe in this kind of ownership.)

The assignment contract commits the foundation to setting distribution
terms that permit free redistribution.

Often we don't want to do the work of starting to distribute a program
right away.  There are many things which we will need in order to have
a complete system but which aren't really useful until the rest of the
system is done.  But signing the assignment does not stop you from
distributing the program yourself--as long as you do so under the GNU
terms.  You don't have to wait for us to start distributing.  You can
start distributing as soon as you attach our standard copyleft to the
files.  (Ask for our advice on how to do this.)

The assignment contract we normally use has a clause that permits you
to use your code in proprietary programs, on 30 days' notice.  (The 30
days' notice is there because, through a legal technicality, it would
improve our position in a suit against a hoarder.)  Although we
believe that proprietary software is wrong, we include this clause
because it would serve no purpose to ask you to promise not to do it.
You're giving us a gift in the first place.

You don't need to invoke this clause in order to distribute copies as
free software under the GNU GPL, since everyone is allowed to do that.

* Releasing it yourself.

You can release a program yourself under copyleft distribution terms
such as the GNU GPL.  (In order to accept the program as GNU software,
we would have to be happy with your choice of terms.)  This does not
require a contract between you and the FSF, but we would appreciate
having a signed piece of paper to confirm your decision.

If someone violates your terms--for example, if someone gets a copy
from us, and uses it as a basis for a proprietary product in violation
of the terms--we cannot sue him.  You would have to sue, or he gets
away with it.

* Public domain.

If you put the program in the public domain, we prefer to have a signed
piece of paper--a disclaimer of rights--from you confirming this.  If the
program is not very important, we can do without one; the worst that could
happen is that we might some day be forced to stop using it.

The law says that anyone can copyright a modified version of the public
domain work.  (This doesn't restrict the original, which remains in the
public domain; only the changes are copyrighted.)  If we make extensive
changes, we will probably do this and add our usual copyleft.  If we make
small changes, we will leave the version we distribute in the public
domain.

* What about your employer?

If you are employed to do programming, or have made an agreement with your
employer that says it owns programs you write, we need a signed piece of
paper from your employer disclaiming rights to the program.  It should be
signed by a vice president or general manager of the company.  If you
can't get at them, it is almost as good to find someone who signs licenses
for software that is purchased.  Here is a sample wording:

  Digital Simulation Corporation hereby disclaims all copyright interest
  in the program "sample.el" (a program to direct assemblers to make passes
  at compilers under GNU Emacs) written by Hugh Hacker.

  <signature of Mo Ghoul>, 1 April 1987
  Mo Ghoul, President of Vice, Digital Simulation Corp.

The description of what the program does is just to make it clearer
what the disclaimer covers.

If what you did was change an existing program, it should say this:

  ...in the changes and enhancements made by Hugh Hacker to the
  program "sample.el".

* Did anyone else contribute?

If someone else contributed more than a few lines here or there to the
program, then that person too is an author, and that person too needs to
sign papers just as you do.  So may that person's employer.  However, if
his contribution is just a fraction of the whole work, it is satisfactory
if he disclaims his own rights, even if you are assigning yours.  (If just
the minor contributors' work goes in the public domain, that doesn't leave
much of a loophole for hoarders.)

If you incorporated packages which you found floating around as "public
domain", we might still want to track down their authors, to get
disclaimers to reassure us that they really are in the public domain.  So
keep track of what these packages are and who wrote them.

* A reminder:

In working on a project for GNU, DO NOT study and follow any Unix
sources or other non-free software that might have any bearing on the
project.  Don't refer to them at all, unless you are forced to for
non-GNU reasons.

It is not considered a serious problem if you have read Unix sources
or other non-free source code in the past for other purposes, provided
you don't copy anything in particular from them.  However, referring
to them while you do the work could cause us legal problems later.