What "ground rules" for imperialism in africa were formulated at the 1884-1885 congress of berlin?

The ground rules mainly focused on land acquirement during the imperialization.

1. The european nations agreed on ruling the colonizations of africa

2. If the land was truly does not belong to any party during that time, one party could simply claim that land without any challenge.

3. If on some circumtances, the land is claimed by other party, the dispute shall be settled through concession under treaty.