<SearchParameter xmlns="http://hl7.org/fhir">
  <id value="NamingSystem-period" />
  <url value="http://hl7.org/fhir/SearchParameter/NamingSystem-period" />
  <name value="period" />
  <status value="draft" />
  <experimental value="false" />
  <publisher value="Health Level Seven International (FHIR Infrastructure)" />
  <contact>
    <telecom>
      <system value="url" />
      <value value="http://hl7.org/fhir" />
    </telecom>
  </contact>
  <contact>
    <telecom>
      <system value="url" />
      <value value="http://www.hl7.org/Special/committees/fiwg/index.cfm" />
    </telecom>
  </contact>
  <code value="period" />
  <base value="NamingSystem" />
  <type value="date" />
  <description value="When is identifier valid?" />
  <expression value="NamingSystem.uniqueId.period" />
  <xpath value="f:NamingSystem/f:uniqueId/f:period" />
  <xpathUsage value="normal" />
</SearchParameter>