<StructureDefinition xmlns="http://hl7.org/fhir">
  <id value="custom-questionnaire-response" />
  <url value="https://simplifier.net/resqplus/StructureDefinition/custom-questionnaire-response" />
  <name value="CustomQuestionnaireResponse" />
  <status value="active" />
  <description value="Custom profile for PHQ-9 QuestionnaireResponse" />
  <fhirVersion value="4.0.1" />
  <kind value="resource" />
  <abstract value="false" />
  <type value="QuestionnaireResponse" />
  <baseDefinition value="http://hl7.org/fhir/StructureDefinition/QuestionnaireResponse" />
  <derivation value="constraint" />
  <differential>
    <element id="QuestionnaireResponse.item.answer.valueCoding">
      <path value="QuestionnaireResponse.item.answer.valueCoding" />
      <min value="1" />
      <type>
        <code value="Coding" />
      </type>
      <binding>
        <strength value="required" />
        <valueSet value="https://simplifier.net/resqplus/ValueSet/phq9-common-answers" />
      </binding>
    </element>
    <element id="QuestionnaireResponse.item">
      <path value="QuestionnaireResponse.item" />
      <min value="1" />
      <constraint>
        <key value="obligatory-question" />
        <severity value="error" />
        <human value="A response is required for this question" />
        <expression value="answer.exists()" />
      </constraint>
    </element>
  </differential>
</StructureDefinition>