ELPA license, LGPL + additional restrictions
(Please CC me on replies, as I am not subscribed currently).
The development version (not in testing/unstable for now) of cp2k, which
is under the GPLv2+ itself has just added support for the ELPA library:
ELPA's homepage is here:
Besides the hoops one has to jump through in order to obtain ELPA from
there (register and/or email, there does not seem to be a public file
release or repository available at this time), they say ELPA is licensed
under the LGPL with some additional clauses. I assume the copy in the
CP2K repository is a verbatim copy of theirs:
It says this:
Licensing and copyright terms for the ELPA library:
ELPA Consortium (2011)
Copyright of the original code rests with the authors inside the ELPA
consortium. The copyright of any additional modifications shall rest
with their original authors, but shall adhere to the licensing terms
set forth below.
The code is distributed under ALMOST all of the the terms of the GNU
Lesser General Public License version 3 (LGPL). The full text
can be found in the file "lgpl.txt" in this repository. "lgpl.txt"
makes reference to the GPL v3, which can also be found in this
While we are not allowed to alter the license texts as written in those
files, IN ADDITION our own license prescribes two important
modifications / clarifications to the original lgpl.txt:
- In point 2., clause b) - stating that that you may redistribute
under the terms of the plain GNU GPL - shall NOT apply. In other
words, if you redistribute, you MUST keep the additional permissions
of the LGPL v3 in place.
- If you redistribute, you must redistribute under the terms of the
LGPL version specified here. Using later or earlier versions
published by anyone except the ELPA copyright holders is
When in doubt, talk to us. What we would like to ensure is that the ELPA
code can be used as needed, while providing a strong incentive for
others to contribute their modifications back to the original
My main question would be whether the above can considered
GPLv2+-compatible, i.e. whether cp2k can use this.
The other question would be how to best approach the ELPA folks to
make them feel alright that the LGPLv3+ is fine for them.