Hi all, I've been asked by various people to clarify the license for libzmq, which is LGPLv3 plus a "static link exception" (SLE). That's what I'll do in this email.
The SLE was originally added to help iOS developers, before we moved to a shared copyright model. It turns out that the exception is broad, and worth looking at more closely. The text is at the end of COPYING.LESSER, in the libzmq root. The same license is in CZMQ, and several other projects. Here is the text of the SLE: "As a special exception, copyright holders give you permission to link this library with independent modules to produce an executable, regardless of the license terms of these independent modules, and to copy and distribute the resulting executable under terms of your choice, provided that you also meet, for each linked independent module, the terms and conditions of the license of that module. An independent module is a module which is not derived from or based on this library. If you modify this library, you must extend this exception to your version of the library." In other words, if you link libzmq, or a modified version of it, into an executable, you are exempt from the LGPLv3. If however you distribute source, or a library, or a DLL containing libzmq in any form, it must use the same LGPLv3+SLE license (or a compatible license, such as GPL). I recently added this explanatory note: "Note: this exception relieves you of any obligations under sections 4 and 5 of this license, and section 6 of the GNU General Public License", which is iMatix's understanding. The LGPL uses different terminology than the static link exception, so there is room for argument. Lastly, since libzmq has multiple copyright owners, the license is not negotiable. The clarification note I added is not part of the SLE, but a comment on it. If anyone has a conflicting interpretation of the SLE, please do speak up. - Pieter Hintjens iMatix _______________________________________________ zeromq-dev mailing list zeromq-dev@lists.zeromq.org http://lists.zeromq.org/mailman/listinfo/zeromq-dev
