http://hl7.org/fhir/StructureDefinition/questionnaire-itemControl|4.0.1

The type of data entry control or structure that should be used to render the item.
NameFlagsCardTypeDescription & Constraints
Extension
0..1E.g. Fly-over, Table, Checkbox, Combo-box, Lookup, etc.
 
extension
?..0
 
url
?..?
 
value[x] *
1..? ItemControl (extensible)
 
 
valueCodeableConcept *
1..?CodeableConcept ItemControl (extensible)