LGPL - A change on the way (Groklaw) [LWN.net]

LGPL - A change on the way (Groklaw)

Posted Jul 14, 2006 3:49 UTC (Fri) by kirkengaard (subscriber, #15022)
In reply to: LGPL - A change on the way (Groklaw) by zlynx
Parent article: LGPL - A change on the way (Groklaw)

Never forget that GPL is not a renunciation of ownership or propriety. It is not Public Domain. It is freedom ensured by minimal necessary restrictions. Code you write, you control. Code you release as GPL, you still control. You have merely given sweeping use permissions to the users of your code. You have ensured that your code will remain available under that license, no matter what else happens.

Your hypothetical Group B is violating the license on Group A's code by modifying the downstream license. Group B only has scope to choose licensing on new code written by Group B.

From GPLv3:

"10. Automatic Licensing of Downstream Users.

Each time you redistribute a covered work, the recipient automatically receives a license from the original licensors, to propagate and modify that work, subject to this License, including any additional terms introduced through section 7. You may not impose any further restrictions on the recipients' exercise of the rights thus granted or affirmed, except (when modifying the work) in the limited ways permitted by section 7. You are not responsible for enforcing compliance by third parties to this License."

Anyone receiving code from Group B receives Group A's code under the license as dictated by Group A, the original licensors.

"7. License Compatibility.

When you release a work based on the Program, you may include your own terms covering added parts for which you have, or can give, appropriate copyright permission, as long as those terms clearly permit all the activities that this License permits, or permit usage or relicensing under this License. Your terms may be written separately or may be this License plus additional written permission. If you so license your own added parts, those parts may be used separately under your terms, but the entire work remains under this License. Those who copy the work, or works based on it, must preserve your terms just as they must preserve this License, as long as any substantial portion of the parts they apply to are present.

Aside from additional permissions, your terms may add limited kinds of additional requirements on your added parts, as follows:

* a) They may require the preservation of certain copyright notices, other legal notices, and/or author attributions, and may require that the origin of the parts they cover not be misrepresented, and/or that altered versions of them be marked in the source code, or marked there in specific reasonable ways, as different from the original version.
* b) They may state a disclaimer of warranty and liability in terms different from those used in this License.
* c) They may prohibit or limit the use for publicity purposes of specified names of contributors, and they may require that certain specified trademarks be used for publicity purposes only in the ways that are fair use under trademark law except with express permission.
* d) They may require that the work contain functioning facilities that allow users to immediately obtain copies of its Complete Corresponding Source Code.
* e) They may impose software patent retaliation, which means permission for use of your added parts terminates or may be terminated, wholly or partially, under stated conditions, for users closely related to any party that has filed a software patent lawsuit (i.e., a lawsuit alleging that some software infringes a patent). The conditions must limit retaliation to a subset of these two cases: 1. Lawsuits that lack the justification of retaliating against other software patent lawsuits that lack such justification. 2. Lawsuits that target part of this work, or other code that was elsewhere released together with the parts you added, the whole being under the terms used here for those parts.

No other additional conditions are permitted in your terms; therefore, no other conditions can be present on any work that uses this License. This License does not attempt to enforce your terms, or assert that they are valid or enforceable by you; it simply does not prohibit you from employing them.

When others modify the work, if they modify your parts of it, they may release such parts of their versions under this License without additional permissions, by including notice to that effect, or by deleting the notice that gives specific permissions in addition to this License. Then any broader permissions granted by your terms which are not granted by this License will not apply to their modifications, or to the modified versions of your parts resulting from their modifications. However, the specific requirements of your terms will still apply to whatever was derived from your added parts.

Unless the work also permits distribution under a previous version of this License, all the other terms included in the work under this section must be listed, together, in a central list in the work."

That next to last paragraph is the kicker here. They are free to release their modifications under straight GPL. LGPL terms will not apply to the modified parts of their distribution. It will be lowest-common-denominator Free Software. Group A is perfectly free to use all of it under GPL terms, but only the original Group A code under LGPL terms. They may not relicense the Group B code to LGPL (add permissions) any more than Group B could relicense Group A code to straight GPL (revoke permissions).

It's a feature.

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