<StructureDefinition xmlns="http://hl7.org/fhir">
  <name value="testExtension" />
  <kind value="complex-type" />
  <abstract value="false" />
  <contextType value="resource" />
  <context value="Basic" />
  <type value="Extension" />
  <baseDefinition value="http://hl7.org/fhir/StructureDefinition/Extension" />
  <derivation value="constraint" />
  <differential>
    <element id="Extension.valueString">
      <path value="Extension.valueString" />
      <type>
        <code value="string" />
      </type>
    </element>
  </differential>
</StructureDefinition>