Copyright law is bent and stretched all the time, which is why it is difficult to get a good grip of it. Some major copyright holders are doing all they can to make copyrights seem all-inclusive. It is sometimes simply amazing what is claimed to be protected by copyright. In reality the basic rule of thumb is that copyright is exactly as wide a concept as you can afford to protect. For example FOM can make ludicrous claims about the extent of their copyright to consumers and get away with it, because none of their targets have the finances to outlast them in court.
I think everyone here believes that Harn is copyright material, the question is who holds the copyright.
BERNE CONVENTION FOR THE PROTECTION OF
LITERARY AND ARTISTIC WORKS (Paris Text 1971)
(3) Translations, adaptations, arrangements of music and other alterations of a literary or artistic work shall be protected as original works without prejudice to the copyright in the original work.
Authors of literary or artistic works shall enjoy the exclusive right of authorizing adaptations, arrangements and other alterations of their works.
However, in principle ideas cannot be copyrighted, only specific expression can be copyrighted (this according to WIPO, TRIPS and most copyright acts around the world). Thus Harn or Middle-Earth as ideas cannot be protected by copyrighted, only the works of the respective authors describing these places can be copyrighted. Again, in principle I can draw a map of Minas Tirith and I can write a book about events happening in Minas Tirith, just as long as I don't use parts of the original work doing it.
Robin could not for instance copyright the idea of an island location for FRPing, but he can copyright the Harn FRPing corpus.
Two difficult issues regarding copyright are characters and names. Sometimes a character can be protected by a copyright if it is deemed to be an original expression (like Mickey Mouse), othertimes not. Also in some cases, which are especially relevant to fantasy worlds, names can be considered protected, othertimes not. Usually it is prudent just to avoid using characters and names to avoid these problems. So when I draw the map of Minas Tirith, and I haven't asked permission from the potential copyright holder, it would be prudent not to use the title Minas Tirith for the map. BTW my map of Minas Tirith (if I didn't use the title no matter how obviously it would be Minas Tirith) would be my original work and not a derivative work. I could even sell and profit from it, if I dared to face the onslaught of angry letters, which would surely follow.
I'm sure that Robin would have no problem with anyone making a HARN (High Accuracy Reference Network) map.http://www.sddot.com/PE/roaddesign/docs/harn03.pdf
Another issue to note is that even though copyright notices are customarily used primarily due to past US internal rules, there is no obligation to use these notices. The copyright notice itself does not create or alter copyright, although it might serve as evidence of the perception of relevant rights or act as a warning.
As Robin pointed out that although the very act of publishing something gives one a copyright, according to the Berne copyright convention, publishers of derivative material ARE required to acknowledge the copyright of the source material.