Not liking the terminology in this OpenID spec: "A federation can be expressed as an agreement between parties that trust each other."
As a non-technical example, the US of A is a federation. This implies that Texas and California trust each other. Doubtful.
It's also not the same way we think about the "federation" part of the Fediverse, although I'm not sure that we've ever attempted to crisply define what we mean by federation and not.
@J12t
sounds right to me. trust the other server not to let their users cause problems for the users on my server. opt out not in cause we assume good faith. more like the articles of confederation than the constitution. no greater authority that we all have a say in.