The Is-modifier section could be clarified if the sentence below indicated which element (i.e. status) was being discussed. I recommend changing:

FROM: The value of element affects the entire meaning of the resource - if it is set to refuted, the entire resource must be understood differently, and so it is not safe for implementations to ignore it

TO: The value of the status element affects the entire meaning of the resource - if it is set to refuted, the entire resource must be understood differently, and so it is not safe for implementations to ignore it