I am writing a Celtic themed product, and using OGC material from Mongoose's Slaine RPG. The PI declaration lists a number of terms they claim as PI, and I have a problem with it. While some of the various terms claimed as PI are certainly unique to the Slaine series, there are others that are part and parcel of Celtic myth and lit.
The following terms all are claimed as PI and also appear in my Oxford Dictionary of Celtic Mythology:
Slaine, Warp Spasm, Tir Nan Og, Fomorian, Red Branch, Fir Bolg, Enech, Cromlech.
Slaine is a character in the early stories. Warp spasms are traced to Cuchulainn, though he wasn't the only hero to become distorted during a rage. Tir Nan Og is the mythical Land of Youth; though the common Irish spelling is Tir na nOg, Tir nan Og (or Tir Nan Og in some cases) is the Scottish Gaelic spelling (as an aside, the book also claims Land of the Young as PI, and while my dictionary lists only Land of Youth or Land of the Ever-Young, I have certainly seen Tir nan Og called Land of the Young in other academic works). Fomorian is the name of a mythic Celtic race, as is Fir Bolg (or its alternate spelling, Firbolg). The Red Branch is an older name for the Ulster cycle, and a popular name for the band of warriors based out of Emain Macha. Enech is the old Irish word for face (as in "saving face" or honor). Cromlech is another Gaelic word (more used in Wales and Cornwall, though not exclusively) for
The only thing I can think of is that I can't use the Slaine universe's interpretation of these terms, but I don't see any way in which they could stop me from using these terms simply as terms; that would be like me claiming as PI Olympus, Achilles and so forth.
Personally I have a mind to simply ignore the PI declaration as it applies to these terms, which have obviously been in use before the Slaine comic or the game, but I wanted to ask for thoughts on the matter.
I am annoyed that I even have to bring this issue up when it comes to terms that are clearly part of the public domain. I am even more annoyed because this is something that I keep seeing pop up in products. This is how I interpret the OGL in regards to PI (and I am not a lawyer):
If a term is part of the public domain, you cannot PI it. You can PI a particular expression of a term, but you cannot claim any term as PI just because.
We have reached a conclusion, backed by Ryan Dancey and Clark Peterson, both people I respect in their understanding of the particularities of the OGL, that claiming those terms as PI is irrelevant as I can draw them from the public domain. I realize I cannot use the Slaine RPG's particular expression of those terms, but they sure as hell can't keep me from naming a character Slaine, from descriving Celtic warp spasms, and having Tir Nan Og (or Tir na nOg, or Tir nan Og) as a location in my product.
It amazes me that we still have problems like this (along with people who do not know how to do the Copyright declaration--Section 15--of the OGL) after five years of dealing with the OGL.