<<Can you give an example of PI in some actual work that is trivial to circumvent?>>
There's a supers game on the market that PI's "Power Points" (read "character points") and "Hero Points" (read "plot points").
But they opened up the method by which they costed things as OGC, but relied on the PI'ing of Power Points as their means to secure their point costing system. If I can source in stuff from somewhere else, I can claim that "Character Points" is a concept in the public domain, or I can probably even find other games that have "Power Points" in them. I leverage the OGC power creation method to recreate all the costs, and source in "Hero Points" from another d20 supers game.
That's a rule, and I know there are people who think "concepts" and "language" do not support rules concepts, and rules _expression_, but several vendors do. It's pretty trivial in almost any instances that aren't incredibly obscure.
Take, for example, the most recent WotC PI declaration: "Gray Waste of Hades". He that sounds like something they aren't gonna declare as a trademark. Sounds like something that can't be copyrighted. My friend drafts a one paragraph story containing the phrase. I source the phrase from my friend's story. Circumvention of the PI declaration if the PI declaration functions as "white out" and not as a "prohibited list".
Spell names? Spell names can only receive copyright protection as a collection. Individually they have no protection under copyright law. If you are already licensed the spell text, but not the name, and you want to reprint just that one spell -- hey, get the spell name from a friend, attach it to the licensed text.
If you can casually source in uncopyrightable stuff from outside sources then you can trivially end run a lot (but not all) PI declarations of names, concepts, poses, themes, etc. that are not otherwise protected under pre-existing IP law.
The only thing that is tough to circumvent are things that are already protected under trademark and copyright laws. That would chalk PI as having about nothing to do with protecting your properties.
PI would then not be a protection of any serious kind for many things on the PI list (the "you may not use PI" clause would be kinda weak). PI would then be a designation, not of things protected, but of things that just aren't licensed to you. In other words, "OGC is everything in chapter 1 except the following character names: ..." Those terms aren't licensed to you, but they aren't really offered any particular protections of any substantive level if they don't already have trademark protections since people can "source them in" from other documents, and since the terms themselves aren't protected, a million people could write down those character names.
Now a court might offer very limited protection to a specific combination of uncopyrightable materials and licensed materials, but if the court granted such a limited copyright protection it would be because they granted it under copyright law, not because the "white out" method of viewing PI would provide any real hurdle to a lot of the more abstract things on the PI list.
And perhaps this is where the protection would exist, but if so, again, it's not the PI portion of the license offering protection, but copyright law. PI would simply be a way to highlight things that aren't licensed, and the "you may not use PI" clause would be defanged.
Lee
