<StructureDefinition xmlns="http://hl7.org/fhir">
  <id value="signal-documentreference" />
  <url value="https://signalbhn.org/fhir/StructureDefinition/documentreference" />
  <name value="SignalDocumentReference" />
  <title value="DocumentReference Profile" />
  <status value="draft" />
  <fhirVersion value="4.0.1" />
  <kind value="resource" />
  <abstract value="false" />
  <type value="DocumentReference" />
  <baseDefinition value="http://hl7.org/fhir/StructureDefinition/DocumentReference" />
  <derivation value="constraint" />
  <differential>
    <element id="DocumentReference.category">
      <path value="DocumentReference.category" />
      <binding>
        <strength value="required" />
        <valueSet value="https://signalbhn.org/fhir/us/core/ValueSet/signal-filerepo-classification" />
      </binding>
    </element>
  </differential>
</StructureDefinition>