GPL vs LGPL, in the context of adns ----------------------------------- Several people have asked me to release adns under the GNU Lesser General Public Licence (LGPL, formerly the Library GPL) instead of the `stronger' GPL. This file is intended to answer most of these questions. If you still have questions or comments, please mail me at . Typically there are two or three kinds of situation where people make this request: the first is where someone is developing a proprietary program and wishes to make use of adns but doesn't wish to make their program free software. The second case is where a free software project is currently using an MIT-like licence and fear `GPL infection'. The third case, which often overlaps with the second, is where another free software project currently using a GPL-incompatible licence, wishes to use adns. 1. Proprietary applications of adns ----------------------------------- So, let me get this straight. You're writing a proprietary program, by which I mean that you will not be distributing source code and not allowing users to modify and share your software; most likely you are doing this for your own (personal or corporate) financial gain. However, you want to take advantage of adns, software which I have spent my time and effort on, and which I release as free software so that everyone can improve, share and use it. Don't you think that is a little hypocritical ? I'm sorry, but I don't want you to just take my nice convenient software, without giving something back to the free software community or giving the same rights to your users as I do to you. If you really aren't the nasty kind of person I've described here, for example if you have a good reason other than your own selfishness for wanting to restrict distribution of your program, then perhaps you should contact me to discuss it. 2. GPL-avoiding projects (MIT licence, et al) --------------------------------------------- Some free software projects prefer to avoid the GPL and other licences which force the software always to be free. Instead they use something like the MIT X licence, which allows proprietary versions of their software. I have to say that I don't understand why they do this, and think they are misguided, but that doesn't mean that they don't have a perfect right to. Some of these people think that merely writing to an interface provided by GPL'd software will cause their program to become GPL'd too, even if they don't distribute the GPL'd software. I don't think this is the case. I'm perfectly happy for non-GPL'd software to refer to adns in its source code or executables (eg, dynamic linking). However, if you distribute adns yourself then whether a program which uses it needs also to be GPL'd depends on the interpretation of the `work as a whole' and `mere aggregation' parts of the GPL. Whether you are distributing a `work as a whole' might depend on many things, but they key one to me is what the appearance is to a user. If the user knows that they are getting a collection of software rather than a single product, then it's probably an aggregation which works together. So, you can distribute both your (i) non-GPLd program source and/or binaries and (ii) adns source code or even binaries (provided the adns source is available as per the GPL), eg from your website, provided the user can tell that these are separate works and can tell which parts are which. But, if you package your program and adns together so that the user is no longer aware of adns as a separate work, then I think you are distributing a `work as a whole', and the whole work including adns and your software which depends on it must be GPL'd. This is of course not a problem if your non-GPL licence is GPL-compatible (see the next section): it just means that _when the whole lot is shipped together as one work_ it is covered by the GPL. People who wish to make proprietary works based on just your code can do so, provided they (or you) arrange for something to fill the hole left by the lack of adns. 3. GPL-incompatible free software licences ------------------------------------------ Regrettably, there are a number of free software licences (and semi-free licences) in existence which are not compatible with the GPL. That is, they impose restrictions which are not present in the GPL, and therefore distributing a whole work which contains such a program and a GPL'd program is not possible: either the work would have to be distributed under the GPL (violating the restrictions made by the original author), or under the GPL-incompatible licence (violating the GPL). I may be prepared to make exceptions for such a licence. Please contact me at with the full text of the GPL-incompatible licence. However, I would prefer it if you could use a GPL-compatible licence for your project instead. There are a couple of common extra restrictions, and I make some specific extensions to my licence for adns below. 3.1. BSD advertising clause and endorsement restriction The most notable and common extra restriction found in free software licences is the `obnoxious BSD advertising clause' (see Richard Stallman's article on the subject, available from www.gnu.org) and the endorsement restriction. The problem with the advertising clause isn't that the sentence required, referring the the Regents of the UC Berkeley, is awkward. The problem is that if everyone contributing to a large project gets such a mention the number of sentences required becomes very large; however, it is unfair for some people to get credit and others not to. I disapprove of these clause, but I recognise that it may be difficult for some people to get them removed from particular programs. So, I hereby make an extension to my licence for adns: You may alternatively distribute adns under the GNU GPL version 2 with the following banner and either one or both of the following additional restrictions, to be inserted at the end of section 1: ADDITIONAL RESTRICTIONS: (The permissions granted in this licence only apply if you comply with the following restrictions:) (a) All advertising materials mentioning features or use of the Program (or a work based on the Program, GPL section 2) must display the following acknowledgement for each author, copyright holder or group of authors or copyright holders: This product includes software developed by PERSON OR GROUP. where PERSON OR GROUP is the name of the (group of) authors or copyright holders, in the form in which they reasonably wish themselves to be identified in such acknowledgements. A reasonable alternative form of words must be used if requested by the person or group. The desires of the persons or groups are to be inferred from statements made about the desired form of such acknowledgements by these persons or groups in their own copyright notices and licences. Such statements are to be considered part of the appropriate copyright notice that the GPL requires you to publish (section 1). This credit must be given for every author and copyright holder of the Program or the work based on the Program, in so far as it reasonably possible to determine who the author(s) and copyright holder(s) are. (b) None of the names of the copyright holders and authors of the Program or works based on the Program may be used to endorse or promote the Program or works based on the Program without specific prior written permission. Any rephrasing of this restriction provided by authors or copyright holders in their copyright notices is to be retained as part of the appropriate copyright notice that the GPL requires you to publish (section 1). --- Ian Jackson 9.5.1999 Local variables: mode: text End: