Zopistas, I've heard a lot of GPL issued raised recently and I want to say a couple of things to hopefully end the subject. I don't mind you pointing replies to me if they aren't of general interest [hint ;)] Firstly, read the GPL. It sounds like some of you talking about it haven't (or have forgotten its contents). That'll clear most things up. Its ambiguousity is limited to very technical cases such as dynamic linking etc. Even in that case, the use of the GPL'd C Header files at compile time can be taken to be indication of agreement to the GPL (even the use of header files produces a legally defined "derivative work" - one look at the sql.h files MS distibute to make that clear. The lack of court testing is irrelevent too, that hasn't happened becuase no one has stood to gain from it - a good indication that they'd lose. If any company found real legal fault with the GPL where they could take code and not be force to comply, they would have done. The legal issues surround very specfic cases, not the entire license. The Objective C front end to GCC is there because NeXT backed down after admitting a futile case. The "its not been tested in court" argument applies for many many licenses and EULAs but you can bet that the flip side is true also - the reason its not got to court is becuase everyone seems to be agreeing to it out of court - a precedent no court would ignore if it ever came to it. The compatibility issues of [MQZ]PL / GPL are generally cases where some case is strongly demanded which the GPL strongly rejects. Things like choice of law, the right to take patches for non Free use etc would cause incompatibility due to the difference in the rights assigned to the user under GPL and those not allowed under the other. This DOESN'T stop you using the GPL in Zope though if you specifically allow it on your side and the creators also do. As far as I know, DC hasn't forbade modules under GPL to be used, or rather they have made the Product interface "open" enough to allow even proprietry Products to be written and used. Of course, this is module authoring (even Linux kernel modules need not be under GPL). In the case of taking ObjectManager.py and adding things to it, that stays under ZPL like it or not (even your changes). That is where the two are incompatible. You can take embed GPL code in BSD code - that's why they are "compatible". To call that "pilfering" but not mention companies who take BSD code and don't even share their extenstions is a little harsh I think (the windows FTP command comes to mind). I don't think that using a GPLd product in Zope (via the Product interface) would mean you have to give source away for _your_ Products and site code which uses them. They are distinct and bound only by the open interface Zope provides. If, however, you change the GPL'd Product, then you will have to stick with the GPL. Either that or re-implement. And yes, you will have to offer the GPL'd parts under the GPL terms if you distribute the whole. A real world case of this? There are many commercial products that include GPL code. I've seen it used in firewalls and printers and in all cases the GPL parts where distibuted under GPL of course. The distinct parts (non linked, seperated by "open interface" - be that as seperate processes, kernel modules etc) are not always available under GPL. Philips' Tivo site has their changes to Linux under GPL available. You won't find their MPEG suite though - shame ;) The GPL has no direct stance on making money or otherwise. You can sell GPL'd code for all you like, changes or none. It only governs the rights assigned to those YOU distribute it to (not the world). However, that one customer then has the right to distribute to the world. Unless you are bloody good with your support and documentation, they won't need you. If you are good that's a different matter. The choice of license on an open project isn't, from the real world, an indication of how well it'll do commercially either. Yes, apache, XFree86, Perl, Python etc etc all use non GPL licenses and that's good for them in some cases - their aims are DIFFERENT to FSF/GNUs. Besides, Linux, GNOME and the GNU compiler tools get just the same amount of commercial recognition (Mozilla is now also under GPL), if not more and from just the same people. That's about it. The only really clarifcation needed to clear this all up is... 1) DC to say Products do not have to be under ZPL and to deem their Product API an open interface akin to Linus' statement on the Linux kernel module interface or RMS's on calling GPL'd apps through the System() call. 2) Any GPL code that effects Zope's core will have to be deemed under ZPL while running with Zope. I'm not sure any Products do this but in the case of any, this would sort it out. Yes, its really just a dual licensing scheme but many do that - Mozilla, Perl and Qt amongst them (and all with the GPL alongside their other license). In the case of the first being granted, its only the latter that would cause "distribution concerns" I think. Thankfully its also a lot more unlikely to happen. Phill phill@gnu.org