The goal: Unified copyleft license for free information.
The problem: Not every piece of information has a source code, and there are cases where source code availability can not provide full freedom of usage, modification, redistribution, and credit. The solution: Define information source as a full history of published modifications to the licensed piece of information in preferred form for making modifications. Distribution of modified versions of the piece should require that such source is preserved by respective authors of individual modifications, and its availability is guaranteed by (a) providing a valid reference to how the source can be obtained for a charge no more than the cost of physically performing source distribution, (b) updating the reference on request in case it becomes invalid, and (c) providing the source on request in case no other valid reference can be provided. Rationale: For software, modification history is already commonly preserved and published in the form of CVS repositories and other similar version control systems, and is considered essential to the development process. In this case, access to modification history already proved itself instrumental in excercising the freedom of modification. For documentation and other literary works, additional benefit of treating modification history as a source code is that all credit is preserved, and any modifications that change the meaning of a political or otherwise controversial passage are transparent to the reader. This should substantially reduce the need for GNU FDL's Invariant Sections. The main drawback I can see, especially in case of massive scientific data and multimedia artworks, is increased overhead for storage and distribution of free information. The issue of distribution is addressed above by softening the requirement down to at least provide a reference to the source. The issue of storage is more controversial, all I can give is my personal opinion that it is fair to expect that creators keep track of at least their own work, and in case original source is lost even to its creator, 'form preferred for modification' should be chosen from forms remaining in existence. Conclusion: This is not a ready solution, and I expect that debian-legal folks will be able to punch some holes in it, but I hope it contains some ideas that can be useful in solving the ultimate task of creating a unified copyleft license. -- Dmitry Borodaenko
