Licensing question (GPL or LGPL) (Ben Finney)

Sam tzahm at
Tue Jul 5 16:22:51 UTC 2005

> From: Ben Finney <ben at>
>>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.

We would like to use LGPL if we can (for our API), but as we're building
the PD External with a GPL library we might not be able to do that.

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

Ah, excuse me... I meant PD as in "Pure Data", a modular audio program ( ). It's 'plugins' are called

>>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?

We created the API ourselves however using other libraries (see below).

>>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).

Yes, we know we either have to release as GPL or LGPL, that's what we
want, but let me rephrase the question:

Our API builds on LibcURL (MIT), TinyXML (zLIB) and LibSnd (LGPL)
=> can we release our API as LGPL?

Our 'pure data plugin' uses above + uses Flext (GPL), thus it can only be
released under the GPL, is that right?

>>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.

We are the copyright holders. But our API uses other libraries, hence
this mail.

I think the confusion arose from my usage of the abbreviation PD for
Pure Data - apologies for this...


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