Birgitt: This brings up for me the problems of not at least copyrighting the terms. Harrison Owen's coining of the name is associated with a particular methodology. Even if he didn't accredit people in Open Space he could have copyrighted the name and then what? I'm not sure if we'd be any further forward.
On the other hand, when we read about a methodology in a book which is openly published, we are free to take information and use it in ways that customize it to our needs. However, the big problem is in acknowledging sources. It's a double-edged sword. Do I say that this method is derived from something if I've substantially or critically changed it? The person who developed it should get credit but not the damage from poorly led processes. I don't have any answers. Only more musings about the issues. Esther