It's only "property" if it can be defended or if it is respected.

On the "defensive" front, it's hard to contain and restrict the use of an idea.

On the "respected" front, I could see the possibility of a voluntary agreement to share an idea in exchange for restrictions on its use. But even then, it is still hard to contain that idea and keep it from others figuring it out. So private agreements would likely only have short term effectiveness