The owin spec references common keys, replicate some text but does not include it. It mixes together a whole bunch of concepts.

I suggest we move the "startup properties" to the main owin spec, and as suggested before link to a revamped keys registry, with the definition of what a startup key is. It has the advantage of allowing the owin and the middleware specs to point to the same concept, and have both point to the key registry.

We have two keys to grandfather if we rename all to host, so while keys for startup should be defined in server, we would define the two host ones as being named like this for back compat only, and discourage the addition of any further host keys, and making them a MUST NOT for addition to the registry.