Hello,

I will try to write down, what I understand starting at the
simple stuff.

Disclaimer: I am not a lawyer.


1. amforth was released initially under GPLv2

The initial import of files was in 2006
> Date:   Mon Oct 16 08:58:30 2006 +0000
the LICENSE.txt file lists GPLv2. In particular, amforth was
never dual licensed.

> https://sourceforge.net/p/amforth/code/2/tree/trunk/LICENSE.txt


2. license was changed to GPL v3 in 2014

The change occured wit r1687 on
> Date:   Tue Oct 28 20:17:40 2014 +0000
which lead to some heated discussion at the time. If I remember
correctly that license change was done in order to absorb a body
of some other Forth code into amForth, and said code was GPLv3.
And if I still remember correctly it had todo with a new target
(msp430 or arm).

> https://sourceforge.net/p/amforth/code/1687/
> https://sourceforge.net/p/amforth/code/1687/tree/trunk/LICENSE.txt


3. Forth is peculiar, loading a programm text always extents the
original Forth in such a way, that the result is a derived works
of the underlying "original" Forth. Therefore, if said result is
wanted to have a specific license, the only way forward is to
start with a Forth featuring a suitable license.

> https://amforth.sourceforge.net/faq.html#what-means-the-gpl-for-my-programs

3.a. If you use your amforth+programm on your system, everything
is ok.

3.b. If you give amforth+programm to your neighbour, then the
GPL forces you to also give away the source code (original, your
changes to the original, your additions i.e. your program). You
cannot get away with giving your neighbour only a compiled
(working) system. This is the point at which you turn into a
"distributor".


4. Aggregation

Things get more interesting, if you aggregate source code from
several projects into a new thing. This is the point, where
Licence files get lengthy. For an impressive imho example see
the debian/copyright file in the sources of u-boot.

As far as I understand, the derived work may still be published
as GPL, but not any more permissive, if any of the used sources
are explicitly licensed GPL.


5. Why does this question come up?

> From: John Sarabacha <[email protected]>
> Date: Fri, 6 Feb 2026 08:31:38 -0500 (2 days, 4 hours, 39 minutes ago)
>
> ... my version (split/fork) changed significantly from the
> original work, which is authored by me, to change the
> licensing of these changes from GPLv3 to MIT.

I understand, that you want to relicense the derived work
consisting of these inputs

- amforth
- your changes to amforth
- your program

as a whole under the MIT License. If this is correct, then I
would point to that entry in FAQ "what means the gpl for my
programs" and conclude: Relicensing of

- amforth
- your changes to amforth

is not possible. You can license your program code any way you
want, however, the Forth peculiarity (see 3. above) will extent
amforths GPLv3 license to the result.

I repeat: the sticky point is distribution of the derived work
to someone else.


I hope that this clarifies the situation.

Cheers,
Erich

-- 
May the Forth be with you ...


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