Jeez, thanks.
I'll try to reply but it is tough and it is really a case by case thing.
Closing spell names has been done pretty commonly. So has closing monster names. I have always taken that to mean the person is closing their incarnation of that particular name. For example, when you designate as PI (my favorite example) the "frost ape" there is no way in the world that means no one can ever make another frost ape. What it means is you are declaring as your PI the "total package" of the frost ape--the name combined with your art for it and your description of it and its totality. I dont think there is any publisher that would consider it a violation if you made your own "frost ape" after they had made one, unless all of a sudden it had the same description and the same special things about it that made it unique (and i dont just mean that it is an ape that lives in the cold).
There is nothing in the OGL (IMHO) that requires proper names to EVER be considered derivative. They are fair game (IMHO) to be closed. Now that may bring a new set of gripes that I will get in to here for a second.
1. There are the gripes that a person CAN'T do something.
2. Then there are the gripes that people SHOULDN'T do something.
3. Then there are the gripes that people should do something DIFFERENTLY.
People who talk about OGL violations often mix all three of these up.
Arguing over the clarity of an OGC designation often is a 2 or 3 above, not a 1. In other words, it doesnt truly violate the license, people just think you shouldnt do it that way (for example, define OGC as narrowly as possible rather than opening up as much as possible) or that you should do it differently (for example, using a font or a box of text to designate OGC rather than a broad textual designation in the back of the book).
So back to closing names. I dont think closing proper names EVER falls under 1. You CAN close proper names.
The question becomes SHOULD you do it, or perhaps should you do it DIFFERENTLY.
Sometimes that depends on the content and how you want to handle it.
I will be honest. From a publisher's standpoint it is easier to close ALL the monster or spell names and then make ONE simple license that allows their use (like we did in the original Relics and Rituals) than to pick and choose which words of which names are closed and which are open.
Another reason to close them all is that it is safer. One problem with being so detailed and picking and choosing is that you might make a mistake and mis-label something as open that should be PI and then you just screwed yourself. So the broader tactic of "closing all monster names" or "closing all spell names" is safer for the particular PI--particularly for larger works like a hardback book like AU.
The interesting issue you raise is closing RULES that seem to be derivative. I can tell you that this issue is far from settled even among publishers who have been discussing this issue for some time. There are many good arguments on both sides. For example, you can say that there have been hundreds of game systems and mechanics that existed prior to d20 so to say that all rules in a d20 product have to be derivative by default is (IMHO) way too overbroad. You could certainly come up with new rules and new mechanics that you simply express in terms of resolution with a d20 that doesnt make the rule derivative.
Here is an example. In our new Player's Guide to the Wilderlands (a new setting) I detail the Sage PC class. In a sidebar I talk about tomes of ancient knowledge and encourage DMs to create unique and valuable books that may not even contain spells, just knowledge that may be used to provide a bonus to certain Knowledge skill checks for example. I also talk about some evil books being mind-crushingly alien (kind of a nod to Lovecraft). I detial Will saves and Wisdom damage and some other things. Now, the term "Will save" is a d20 mechanic. The term "temporary (or permanent) ability damage" is a d20 mechanic. Does that mean that the rest of the text of my new idea about books MUST by definition be a derivative rule and thus 100% open? I would say no. I would point to the Call of Cthulhu (non-d20) rules and say, see that rule idea existed before d20 was even invented. The fact I am expressing a similar type of rule in d20 terms doesnt necessarily make it derivative.
The problem is, if that isnt derivative, then what is? It is quite a can of worms.
The point is we have to admit that new rules and mechanics can be created that have nothing to do with d20 and that are simply expressed in d20 terms. If a rule is truly novel, though it is expressed in d20 terms, I think (IMHO) it can be closed.
The other side of the coin, for example, is a new feat. You can close the name but the mechanics of the feat are clearly derived from the d20 SRD. But a good example might be Monte's Talents. That could be closeable content.
The pros of closing stuff (particularly in a broad way) is it is easier for the publisher to handle permission to use content. Most spell names or gods or things like that at some point will have PI in it. For example, there were a large number of spell names in Relics and Rituals that had our unique god names in them and setting or race names. Rather than try to pick through each one, we just PId all the names and then in the book itself provided a short blanket license to use the content in a limited fashion. The other "pro" is that your PI is tighter. To some people that is important as I detailed in the post above.
The con is that some people will gripe based on 2 or 3 above (and some might even gripe based on 1 above) that you SHOULDNT have closed that content or that you should have designated it DIFFERENTLY (and some will say that you CAN'T do it the way Monte did it).
To me the most relevant distinction is for gripes from category 1.
Nobody (publishers included) agree on 2 or 3. Some say open it all (generally people with nothing too valuable to lose), some say close it all. Some purchasers say "I wont buy it if it isnt open" which (IMHO) is rediculous because there are so many reasons why something needs to be closed. Others (the other 99%) of purchasers dont care.
So I guess the bottom line is that I believe some rules are true new inventions and are unique and the simple fact that they use d20 terms to explain them does not mean the rule must be open. That said, I dont offer any opinion on whether or not Monte's stuff is proper or not. I will say this--a lot of people dont like Monte's tight designations, but most of those people are not publishers who dont have to think about things like licensing that content to other people and the problems of protecting your own very unique and valuable intellectual property. One day, believe it or not, d20 will be gone. Maybe three years from now, maybe 30. But if you kept a tight PI designation, you have more content to license later. And I can say this for Monte, he is in this industry for the long haul. I can also say this, he is a great guy who cares a lot about open gaming. Please dont necessarily take his designations (which are the height of internal business decisions) as a reflection of his thoughts about open gaming.
Clark