From: John Stone (
Date: Sun Jul 05 2009 - 20:14:35 CDT


On Sat, Jul 04, 2009 at 09:13:37AM -0400, Roland Schulz wrote:
> Hi,
> is our understanding correct that the 10% clause in VMD is not GPL
> compatible?

It is compatible in that you're free to use it for anything you want,
but, that said, you would not be able to re-license it as GPL code.
So while you're free to use it, it would remain governed under its
original license, just as code using the BSD license, UIUC open source
license, and other licenses remain under their original license.

Also, it is true that if ten different people each borrowed 10% of the code,
that you'd be violating the original license to incorporate those
ten different 10%s into a single code base. I would not see a problem
with us making modules like vmddlopen.[c] Plugin*.[Ch] etc available
under the UIUC open source license (BSD derivative) however, if that
would make it easier for you to use the VMD plugin APIs in other
packages. There's nothing particularly magical or proprietary in
the plugin-related source code in VMD, so I would be happy to
accomodate this if it made things easier for you and others to use
the VMD plugin APIs.

I have already been planning on reengineering things a bit so that
the interesting parts of PluginMgr.* were migrated to the plugin
source tree and compiled into the static molfile_plugin.a so
that the same plugin management code would be shared by
VMD, NAMD, psfgen, cionize, and any other tools that wanted to
make significant use of plugins, particularly the dynamically
loaded shared library variety of plugins, which is the only case
that's very tricky.

If this would address your needs, let me know and I would be happy
to begin working on this with you.

  John Stone

> ---------- Forwarded message ----------
> From: Erik Lindahl <>
> 1) We need to be able to distribute the code as GPL/LGPL (instead of a
> combination of licenses). The 10% clause probably doesn't fly with this,
> since the one could imagine 10 different people copy 10% each, distribute
> as GPL, then somebody else (who gets it under strict GPL, where there
> cannot be side clauses) merges it and has the original code under GPL.
> ------------------------------------------------
> If so, is there a chance that you could release a PluginMgr equivalent
> example code under a GPL compatible license (e.g. University of Illinois
> Open Source License). That would allow other GPL software packages to
> easily use the VMD plugins.
> Roland
> --
> ORNL/UT Center for Molecular Biophysics
> 865-241-1537, ORNL PO BOX 2008 MS6309

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