How should I interpret the request object in node.js express callbacks?

The node.js express module router callbacks receive a request and response object. Dumping the request object is gigantic, so it's pretty tough to interpret where the data I want to read is and how to interpret other properties of the object.

The router documentation doesn't mention anything about how to interpret the request object. Is there any documentation anywhere that is less obvious or a different spec that the object conforms to?