Forum OpenACS Q&A: Re: What is a Community in 5.0?
Our subsite package defines a new community which is a subset of the parent subsite's community. The two notions are tied together. There's no way to create a subsite that does not define a new community.
It's always been that way, the only problem being that until 4.6 it didn't really work :) 4.6 fixed the guts, 5.0 improves the UI making it usable by non-OpenACS experts (or at least moves us in that direction, it's been a moving target and I haven't looked recently to see just how far Lars got before we froze 5.0).
A single word would be better if someone can come up with one.