Licensing question (GPL or LGPL)

Ben Finney ben at
Tue Jul 5 00:01:27 UTC 2005


On 04-Jul-2005, Sam wrote:
> I have a small (big?) question about mixing licenses within a
> project. We'd like to distribute the project as LGPL or, in its
> defect, as GPL.

What are your goals for licensing the project? You're asking for
advice to choose between two licenses, but haven't told us why you
already prefer one or the other.

> The project consists of a PD external built with the flext library
> (the only GPL license of the lot).

By PD do you mean "in the public domain", or something else?

> We want to release a C++ API and, separately, the PD external.

Who is the copyright holder for the C++ API? Is it currently licensed
to you?

> The libraries we're using (for the API) are the following:
> LibcURL –        (MIT)
> TinyXML – (ZLIB)
> LibSnd - (LGPL)
> As said before, the PD external uses flext (flext -
>, GPL) and the above-mentioned API.

The MIT and ZLIB licenses are compatible; they essentially demand the
same terms. You can distribute a combination of these works so long as
you satisfy the terms of both licenses.

A work consisting of work under MIT, ZLIB and LGPL can be distributed
only by satisfying all license terms; the only way to do this is
license the whole work under the LGPL or GPL (and satisfy the terms of
all the constituent licenses).

> Can we release the API as LGPL?

You haven't said what license you currently have for the API. If you
are the sole copyright holder, you can grant any license you like (or
none, or several). If you have received it under license, you need to
satisfy the license terms.

> What licenses would be possible for the external?

If it is in the public domain, no-one has any copyright and you can do
as you like -- essentially as if it were your own work. Continuing to
distribute it as a public domain work would seem the simplest.

Essentially it boils down as:

  - If there are no copyright holders other than yourself (i.e.
    you are the sole copyright holder, or a public domain work) you
    can do as you will and distribute under any license terms

  - If you have received a work under license, you must satisfy the
    terms of that license when you perform an act covered by copyright

  - If you combine works, you must simultaneously satisfy all license
    terms when you perform an act covered by copyright

  - Acts covered by copyright include copying, modifying and

 \            "Madness is rare in individuals, but in groups, parties, |
  `\         nations and ages it is the rule."  -- Friedrich Nietzsche |
_o__)                                                                  |
Ben Finney <ben at>
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