Open Source Licensing: Software Freedom and Intellectual Property Law

The MPL Reciprocity Bargain

Although the MPL is a much longer license than the others I've discussed, when you get beyond the complex words, its reciprocity provisions can be paraphrased very simply as follows: If you create and distribute a Modification to one of the files containing Original Code or previous Modifications, or create and distribute a new file containing Original Code or previous Modifications, those files must be released as Modifications under the same MPL license.

Your newly released files become Modifications for future licensees. One can recognize in this recursive definition how a chain of title is created to ever-more-modified derivative works, with each Contributor adding to the chain. But here, unlike with previous licenses, ...