<<Does the OGL become an umbrella agreement between Wizards of the Coast
and anyone who decides to publish an OGL product; and therefore once PI
is claimed, it is claimed vs. any other subsequent publicactions,
whether derived from that specific work or not?
>>
I'd advise you to search the archives on this for my email address. I think I have a post that notes that it could either be construed to just be an agreement between you and the person immediately before you in the derivation chain OR that the person immediately before you in the derivation chain is given the ability to sublicense materials and act as a proxy for all others upstream from him in the derivation chain (meaning that you'd have to honor all preceding PI declarations, provided that you were reasonably aware of them). There were a couple of other interpretations out there that I thought were worth noting, but had enough holes that I won't repeat them here.
Given the intent and the structure of the license I am inclined to believe that you have to abide by the PI for any work listed in your section 15 which you are reasonably aware of, however, I do not think that this is the sole possible interpretation of this rather vague area of the OGL.
Lee
