The use case we're wanting to support is where we want to have answers to a specific Quesitonnaire (via QuestionnaireResponse) trigger the requirement to complete another Questionnaire be completed via a PlanDefinition.

The QuestionnaireResponse that is entered isn't based on a profile, it's based on the Questionnaire, so want to be able to reference that definition.

(also would like to suggest that maybe ObservationDefinition could also be included)