This is the proposed FEP-61cf: The OpenWebAuth Protocol. OpenWebAuth is the “single sign-on” mechanism used by Hubzilla, (streams) and other related projects. It allows a browser-based user to log in to services across the Fediverse using a single identity. Once logged in, they can be recognised by other OpenWebAuth-compatible services, …
OpenWebAuth has been in use on the fediverse since before WebFinger became so widely used.
Like I said in a previous comment, this FEP was written by reverse engineering the existing implementation. It’s still a proposal so it still has to go through a discussion period where issues like this can be worked out and it can be updated
Oh I see. Thanks!