<<anybody have any idea how this interfaces with the idea that single
book titles can't be trademarked, but book series can be? It seems
to me that "Cyberpunk D20", to use a concrete example, wouldn't be
eligible for trademark status--does that mean the 'D20' in it is
being "used as a trademark"?>>
Query -- if 'd20' is not trademarked already (and this is a hairy subject, since 'd20 System' is trademarked, but one would be hardpressed to trademark 'd20' except perhaps by claiming trademark on 'd20' _only_ when it is used in a product title), then 'Cyberpunk d20' seems like a perfectly valid thing to claim a trademark on.
The book's author might later want to produce 'Cyberpunk d20' hats, jackets, artwork, etc. It looks like a perfectly reasonable trademark _except_ that it's unclear whether "d20" used in the title of an RPG is part of WotC's trademark.
I assume that it is most definitely not unless WotC is busy sending out cease and desist notices to every company using such a product designation. Even if WotC wants to claim they trademark all uses of "d20" in RPG product titles, they'll lose their rights to make such a claim unless they defend the claimed marks in trade.
Can you clarify why you think "Cyberpunk d20" seems to be invalid as a trademark?
Lee
