Subject: Re: Copyright and licensing - a plea to software authors
From: "Theodore Ts'o" <[email-masked]>
Date: Fri, 9 Sep 1994 18:12:57 GMT
Newsgroups: comp.os.linux.announce

[Further discussion on this topic is directed to gnu.misc.discuss
and/or comp.os.linux.misc. These two messages have been posted to
c.o.l.announce to make the Linux community as a whole aware of 
some issues surrounding the GPL; please see discussions elsewhere
if you wish to fight it out. --mdw]

   From: Ian Jackson <[email-masked]>
   Date: Fri, 9 Sep 1994 14:10:28 GMT

   * The GPL does _not_ imply an interface copyright.  It does _not_
   require other people who write independent programs which run on or
   with your software to release their work under the GPL.  The statement
   at the top of the COPYING file in the Linux source tree is redundant,
   other than for clarity's sake and to silence ignorant flamers.

Not quite true.  The FSF/Stallman interpretation of the GPL essentially
amounts to an interface copyright, although they attempt to deny it.  It
is very important that prospective authors understand this before using
the GPL.  It isn't a problem, as long as you and not the FSF control the
copyright.  But in some cases you *do* need to put some disclaimers in
the COPYING file such as is done in the Linux source tree.

It the FSF's claim that it you can not write your own program that uses
the gmp interface, and distribute it using a copyright notice different
than the GPL.  Despite the fact your distribution doesn't contain a
character of GPL, but just merely links against the gmp library, the FSF
and Stallman will still claim that your distribution violates the GPL
copyright on the gmp library.

Stallman and FSF also threatened NeXT with similar GPL copyright claims
to make NeXT release the Objective C front-end under the GPL, despite
the fact that the front-end originally didn't contain a line of GPL'ed
code, but merely called the GPL'ed GNU gcc compiler.  Arguably, the
"right thing" happened in that the Objective C compiler became freely
available.  However, it should be noted that the means to this end was
in essence a threat based on interface copyright.  (I have email from
Stallman to back up this story; I will forward it to people upon
request.)

Now, a number of law professors have stated that the FSF would be
"laughed out of court" if they ever tried to sue someone over this.  But
it is still true that the FSF's interpretation has caused a lot of Fear,
Uncertainty, and Doubt.

This is the reason for the COPYING file in the top of the Linux source
tree, and the reason why Wine was not signed over to the FSF, despite
the FSF's request to the Wine developers.  (After all, Windows uses
dynamic libraries extensively, and according to the FSF interpretation,
anything that dynamic links to GPL code must fall under the GPL; since
in order to run programs like Microsoft Excel and Word, they would have
to dynamic link to GPL'ed code in the Wine emulator, the FSF
interpretation would preclude the use of such commercially available
programs under Wine!)

This being said, please keep in mind that this problem with the GPL is
only a problem with the FSF's *interpretation* of the GPL.  It is not a
problem with the GPL itself!  As long as you, the author, retain control
over the Copyright, it is up to you to decide how you want to interpret
and enforce the Copyright.  You can certainly decide to release things
under terms which are more liberal that the GPL.  For example, Perl is
released under either the terms of the GPL, or Larry Wall's "Artistic
License", at the descretion of the user.  

At the very least, if you are releasing a library under the GPL, please
consider whether you would like it to come under the GPL or the LGPL,
and if it is under the GPL, you may wish to disclaim any interface
copyrights, and explicitly allow poeple to write and distribute code
which calls your GPL'ed routines, as long as their code doesn't actually
include the GPL'ed routines in the distribution, but rather uses them by
reference.  

If your routines are released as a Linux shared library, you should
consider allowing people to write and distribute source and binaries
which link against the shared library, even if their programs don't fall
under the GPL.  Since the FSF believes that any program which
dynamically links against GPL'ed code must also fall under the GPL, if
you wish to allow people to release binaries which link against your
GPL'ed version of curses (for example) it would be wise to explicitly
state that it is O.K. for people to do this.

As the author, you have many rights, and it is definitely a Good Thing
to exercise them wisely.

							- Ted

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