Thanks! I did look around the site quite extensively. That page says

> this is specific to a homeserver implementation

which suggests that it's not documenting a Matrix protocol. Unless Matrix has no standardized client protocol? Are all clients going to be homeserver-specific?

Even so I'd hope there's some document that says "Matrix standardizes server-server communication, client-server communication is out of the scope of this standard and is left to individual implementations" or something like that.

no idea who was smoking what when they wrote that paragraph; i've deleted it.