Let's Put to Rest "Outdoor is/is not FFA" Myths

[QFuzzle]

Twice over this weekend I ran into people who held strongly different beliefs on the topic of mobs that are outdoors and their camp-able status. Irritatingly, I was at the brunt end of both occasions. At one point, a petition was sent out to end the dispute, but the hero never arrived (even though purposeful KS'ing was involved - yikes).

Both instances involved a solo individual challenging a group that was rapidly killing a large number of mobs within an outdoor fort area (BW giant fort, and WW giant fort to be exact).

Taking into considering the Play Nice Policy and having read the "Arbitration / Camps" portion of Rogean's rule post, there appears to not actually be a clear answer to this.

The beliefs consisted of (but weren't limited to):
1) All outdoor mobs are FFA except for a single spawn that's being killed by someone (something like AC would be an example of a highly contested spot that is outdoors and requires a special rule-set to apply to it).
2) If the whole fort/area is being killed proficiently by a group, it's their camp. Not FFA.
3) Certain mobs of the fort are different camps.

There may have been some specific rulings on this matter in the past, but I haven't found them. I'd like to get some clear, definitive, concise GM rulings or posts or something that will clear the air on this topic; something people can point to if there's an issue that people refuse to resolve themselves, and no GM comes to save the day.