description: This extension is used when defining high-level questionnaires that will then be used as a basis for 'derived' Questionnaires that are further refined for use in specific organizations or contexts.  If the extension is present and set to 'true', it means that this item should be considered to be 'optional' from an adaptation perspective and that the question can be removed (i.e. not displayed) in derived questionnaires without impacting the validity of the instrument.  Alternatively, the element can be marked as 'hidden' and 'readOnly' and have a value or descendant item values declared using initialValue or initialExpression.  If the element with 'optionalDisplay=true' is marked as 'required=true', then this second approach is the only means to exclude the element from display.
package_name: hl7.fhir.uv.sdc
derivation: constraint
name: OptionalDisplayExtension
type: Extension
elements:
  extension: {index: 0}
  url:
    pattern: {type: Uri, value: 'http://hl7.org/fhir/uv/sdc/StructureDefinition/sdc-questionnaire-optionalDisplay'}
    index: 1
  value:
    choices: [valueBoolean]
    index: 3
  valueBoolean: {type: boolean, choiceOf: value, index: 4}
package_version: 4.0.0-ballot
extensions: {}
class: extension
kind: complex-type
url: http://hl7.org/fhir/uv/sdc/StructureDefinition/sdc-questionnaire-optionalDisplay
base: http://hl7.org/fhir/StructureDefinition/Extension
version: 4.0.0-ballot