The group of countries tier holds sets of states recorded together: a union they joined, a trade bloc, an alliance, or a part of the world everyone names.

Membership defines the set rather than position, so a group here need not be contiguous and a state can join or leave without the group losing its identity. That is what separates this tier from the continent above it, which is one continuous landmass.

A group does not come between a continent and the countries in it: a country hangs under the group, and the group under a continent. Where several groups cover the same states, only one can be the parent and the others are recorded as members.