Returns, per questionnaire field, whether the form should show it and whether it must be answered. Conditions can read a user field of the person a REFERENCE answer names (e.g. the long-term A1 traveler), so they are resolved server-side. POST rather than GET because the form sends the answers it is holding but has not saved: the field a condition governs is required, as are the fields around it, so waiting for a save would surface the question only once the form was otherwise complete.