On Mon, 22 Nov 2010 21:15:52 +0100 Lukas Baxa wrote: > Hello, Hi! > > I went through the Debian Free Software Guidelines (DFSG) and I have > a question to point number 3 - Derived works - which states: > > # The license must allow modifications and derived works, and must allow > # them to be distributed under the same terms as the license of the > # original software. > > If I understand it correctly, it must be allowed by the original licence > that the license of the derived work is identical (or almost identical). > But it is not required that the licence remains unchanged, it might be > different. Yes, a non-copyleft license may indeed meet the DFSG. A copyleft license is one that requires derivative works to be available under the same licensing terms as the original work, and that forbids the addition of further restrictions. The canonical example of a free copyleft license is the GNU GPL [1][2], but there are other copyleft licenses around... [1] version 2 <http://www.gnu.org/licenses/gpl-2.0.txt> [2] version 3 <http://www.gnu.org/licenses/gpl-3.0.txt> A license which does not include such a requirement (and thus has no copyleft mechanism) is often referred to as a "non-copyleft license". The most famous examples of free non-copyleft licenses are the BSD licenses [3], the Expat/MIT license [4], and the zlib license [5]. [3] 3-clause variant <http://www.debian.org/misc/bsd.license> [4] see <http://www.jclark.com/xml/copying.txt> [5] see <http://www.gzip.org/zlib/zlib_license.html> [...] > As far as I know, GPL requires it. Yes, it does, see above. > But it seems to me that DFSG do not. They do not, in the sense that having a copyleft mechanism is not necessary for a license to be considered acceptable according to the DFSG. And indeed, as anticipated above, several non-copyleft licenses do meet the DFSG. There are also a number of copyleft licenses which likewise meet the DFSG. > Does it mean that it would be possible to include software in Debian > that could be derived and licensed otherwise than the original software? Yes, as long as the software package complies with the DFSG, it can be included in Debian (main). And there are indeed many non-copyleft-licensed software packages in Debian (main), as well as many copyleft-licensed packages. > And does it mean that such derived software might even be a proprietary > software? It means that anyone can take a non-copyleft-licensed software package out of the Debian (main) distribution, modify it, thus creating a derivative work, and distribute such derivative work under different licensing terms than the original ones (as long as the original license is complied with!), even under proprietary terms. However, a proprietary derivative work of a non-copyleft-licensed software package cannot be included back in Debian (main). Please note that this "proprietarization" process is not allowed by copyleft licenses (such as the GPL). I hope this clarifies things a bit. -- http://www.inventati.org/frx/progs/scripts/pdebuild-hooks.html Need some pdebuild hook scripts? ..................................................... Francesco Poli . GnuPG key fpr == C979 F34B 27CE 5CD8 DC12 31B5 78F4 279B DD6D FCF4
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