Conceptual help with model response inputs, outputs, and commands

I'm having a little trouble figuring out how to correctly use inputs, outputs, and commands in a model's response object. From what I've seen in app-hoj and app-poll, inputs provide a hook so that keel knows which data to expect in a request from the generated page. Outputs, allow read-only data to be passed to the UI for display. Commands are still a little hazy to me. It looks like they're used to call other models. They are added to a ModelResponse, but I don't understand how and when one should use a command. Any help would be much appreciated.

- Justin

--
ThatOne Company
http://www.thatone.com/