When GPLv2 talks about works "based on" another work, they mean works that are "derivative works" under copyright law. This is mentioned explicitly in section 0. GPLv2 also uses the term "derived from", which it does not define and is not a term of copyright law. Copyright law gives the copyright owner certain exclusive rights. No one else is allowed to do those things without permission from the copyright owner. The GPLv2 (and most other free software licenses) are designed to give you that permission. They serve strictly to remove restrictions, not to add them. Contrast to a typical commercial software EULA, which might grant to you some permissions, but also will try to stop you from doing things that you are normally allowed to do. For instance, copyright law places no limit on the number of backup copies you can make of software you purchase. All that it requires (at least in the US) is that if you transfer ownership of your copy of the software to someone else you either destroy all your backups, or transfer them with the software. The typical EULA will make you agree to only keep one backup copy. The FSF is quite clear that they intend the GPLv2 to not be a EULA. It only extends rights to you, it does not take any away. Accordingly, when trying to decide what an undefined term like "derived from" means in the context of GPLv2, you should look to copyright law. This makes it clear that they are using "derived" from to mean the same thing that copyright law means by a "derivative work". Gitbox is not a derivative work of Git. The only thing Gitbox is doing that requires permission from the Git copyright owners is distributing an unmodified copy of Git with Gitbox. As long as Gitbox obeys the GPL by making the corresponding Git source available in a way allowed under GPLv2, they have permission. End of story. They tried to clear up some of this confusing in GPLv3: > To “modify” a work means to copy from or adapt all or part of the work in a fashion requiring copyright permission, other than the making of an exact copy. The resulting work is called a “modified version” of the earlier work or a work “based on” the earlier work. -- --Tim Smith -- To unsubscribe from this list: send the line "unsubscribe git" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html