"Questionnaires SHALL indicate which items are necessary using the required property, and the application should use that property to decide when a Questionnaire has been sufficiently auto completed."

This is a weird statement.  This is like saying "systems SHALL put the patient's birth date in the Patient.birthDate element".  Why call out 'required' as opposed to other elements?  Note that satisfying 'required' is only one of the rules that must be met before a QR can be marked as complete.  You have to meet all invariants, meet cardinality rules, ensure entered values are valid, etc.  

What is trying to be accomplished here?