(Deliberately replying to myself since this is not meant as a reply to anyone specifically)
If i try for a moment to ignore the fact that this matter has significant meaning for the OSM community and its social cohesion (the social contract between mappers and data users etc.) this is actually a quite interesting sociological experiment. Because the basis of most comments made does not seem to be the desire to neutrally assess the situation Rory presents here and its implications. This would usually go by considering what if Rory is right and data productions like this would be subject to the ODbL as well as the other way round by considering what if Rory is wrong and you could distribute data sets like this under any license you want. What it seems instead happens here is that people look at the situation and develop a spontaneous reaction in terms of "should this be possible or not" and then specifically search for ways to argue in support of this opinion. This in my experience is how at least 2/3 of all discussions in OSM on legal questions happen meanwhile. This is very non-productive and annoying because it results in what is essentially a negotiation between different interests presented in the discussion instead of actual knowledge and insight into the matter (Erkenntniss in German) as it would result from the scientific approach (i.e. making a hypothesis and scrutinizing it with scepticism). I am not really interested in participating in this kind of interest negotiation - because (a) the results do not depend on who has the best arguments but on who can invest the most time and manpower into the discussion and (b) the results would not actually be an objectively better or more accurate understanding of the situation. From an engineering perspective the idea that adding OSM data can create a derivative database but subtracting OSM data cannot does not hold up of course. I can create a polygon data set of the Earth surface (a simple rectangle in EPSG:4326) and subtract an OSM derived data set of the Earth land masses from that to get a data set of the oceans. According to the hypothesis this would not be subject to the ODbL. This realization (of there being no fundamental difference between subtracting and adding) is - as Rory already explained - not dependent on specific details of the ODbL or the law but derives from elementary logic. -- Christoph Hormann http://www.imagico.de/ _______________________________________________ talk mailing list talk@openstreetmap.org https://lists.openstreetmap.org/listinfo/talk
