Subject: Re: Fwd: Modified GPL Question
From: "Karsten M. Self" <>
Date: Wed, 3 Nov 2004 12:34:23 -0800
Wed, 3 Nov 2004 12:34:23 -0800
on Tue, Nov 02, 2004 at 12:00:32PM -0600, James W. Thompson, II (
> I know this may not be specifically germane to this list but I wanted
> to try my luck at getting a response. Below is a message I sent to
> regarding a 'Modified GPL' concern, the original
> message explains the issue best. I want to know if there is anything I
> am missing on this issue.
> Thank you for your consideration.

What you're attempting to accomplish here is effectively a "dual"
license, though you're extending this to more than two licenses.  This
of itself isn't prohibited, is already done fairly extensively (Mozilla,
Perl,, and the Linux kernel are four prominant projects
so licensed), and isn't a silver bullet.

There's an additional consideration in that you're extending a rather
generous assumption of trust to the OSI, in that you assume any future
(or current) license approved by same would be acceptable to you.  It's
possible tha the group might in future be subverted.  You might even
find those who would argue that it alread has been ;-)

Dual licensing doesn't require you write a new license (though Mozilla
is a project which was released under a novel license, and was later
dual-licensed with the GPL), or even an explicit specification of
licenses -- there's code that has effectively become multi-licensed as
sources from compatible licenses has been intermingled.

You might also look at a BSD/X11 style license (two clause) as sort of a
general-purpose, highly-compatible license, if that's where your
objectives lie.  This is actually pretty unrestrictive, but might
clarify for others what the scope of your grant is.  The "two clause"
(aka "GPL compatible") BSD/X11 licenses are sufficiently nonrestrictive
as to be compatible with pretty much any other terms[1].

Multi-licensing isn't a complete silver bullet.  The transitivity is one
way.  That is, your code might find its way into a GPLd project, but if
you were to copy extant GPL code into your project, the additional
licensing terms wouldn't apply to the GPL'd code, absent specific action
on the GPL'd code's copyright holder(s).  So long as the work as a whole
could be considered licensed under any one of a group of licenses
including the GPL, you'd be OK.  But attempts to license in such a way
as, say, only a BSD/X11 two-clause license allowed, would result in
violating terms of the GPL-only code.

Think that one through a few times if you're confused.

Short answer:

    Consider dual licensing under a set of two or more existing approved
    licenses, selecting those which suit the goals of your project.



1.  In long-standing legal tradition, we'll of course note that
    exceptions are conceivable, and (also in long-standing legal
    tradition) best addressed as a footnote.  Though as a practical
    matter, a BSD/X11-incompatible license would pretty much have to be
    written with that end specifically in mind.

Karsten M. Self <>
 What Part of "Gestalt" don't you understand?
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