<?xml version="1.0" encoding="UTF-8"?><SearchParameter xmlns="http://hl7.org/fhir">
  <id value="example-extension"/>
  <meta>
    <security>
      <system value="http://terminology.hl7.org/CodeSystem/v3-ActReason"/>
      <code value="HTEST"/>
      <display value="test health data"/>
    </security>
  </meta>
  <extension url="http://hl7.org/fhir/StructureDefinition/structuredefinition-wg">
    <valueCode value="fhir"/>
  </extension>
  <url value="http://hl7.org/fhir/SearchParameter/example-extension"/>
  <name value="ExampleSearchParameterOnAnExtension"/>
  <title value="Example Search Parameter on an extension"/>
  <status value="draft"/>
  <experimental value="true"/>
  <publisher value="HL7 International / FHIR Infrastructure"/>
  <contact>
    <telecom>
      <system value="url"/>
      <value value="http://www.hl7.org/Special/committees/fiwg"/>
    </telecom>
  </contact>
  <description value="Search by url for a participation agreement, which is stored as an extension referencing a DocumentReference"/>
  <code value="part-agree"/>
  <base value="Patient"/>
  <type value="reference"/>
  <expression value="Patient.extension('http://example.org/fhir/StructureDefinition/participation-agreement').value"/>
  <processingMode value="normal"/>
  <target value="DocumentReference"/>
</SearchParameter>