FHIR Release 3 (STU)

This page is part of the FHIR Specification (v3.0.2: STU 3). The current version which supercedes this version is 5.0.0. For a full list of available versions, see the Directory of published versions . Page versions: R5 R4B R4 R3 R2

Reference.profile.xml

Modeling and Methodology Work GroupMaturity Level: N/ABallot Status: Informative

Raw XML (canonical form)

StructureDefinition for Reference

<StructureDefinition xmlns="http://hl7.org/fhir">
  <id value="Reference"/> 
  <text> 
    <status value="generated"/> 
    <div xmlns="http://www.w3.org/1999/xhtml">
      <table border="0" cellpadding="0" cellspacing="0" style="border: 0px #F0F0F0 solid; font-size: 11px; font-family: verdana; vertical-align: top;">
        <tr style="border: 1px #F0F0F0 solid; font-size: 11px; font-family: verdana; vertical-align: top;">
          <th class="hierarchy" style="vertical-align: top; text-align : left; background-color: white; border: 0px #F0F0F0 solid;
           padding:0px 4px 0px 4px">
            <a href="formats.html#table" title="The logical name of the element">Name</a> 
          </th> 
          <th class="hierarchy" style="vertical-align: top; text-align : left; background-color: white; border: 0px #F0F0F0 solid;
           padding:0px 4px 0px 4px">
            <a href="formats.html#table" title="Information about the use of the element">Flags</a> 
          </th> 
          <th class="hierarchy" style="vertical-align: top; text-align : left; background-color: white; border: 0px #F0F0F0 solid;
           padding:0px 4px 0px 4px">
            <a href="formats.html#table" title="Minimum and Maximum # of times the the element can appear in the instance">Card.</a> 
          </th> 
          <th class="hierarchy" style="width: 100px">
            <a href="formats.html#table" title="Reference to the type of the element">Type</a> 
          </th> 
          <th class="hierarchy" style="vertical-align: top; text-align : left; background-color: white; border: 0px #F0F0F0 solid;
           padding:0px 4px 0px 4px">
            <a href="formats.html#table" title="Additional information about the element">Description &amp; Constraints</a> 
            <span style="float: right">
              <a href="formats.html#table" title="Legend for this format">
                <img alt="doco" src="help16.png" style="background-color: inherit"/> 
              </a> 
            </span> 
          </th> 
        </tr> 
        <tr style="border: 0px #F0F0F0 solid; padding:0px; vertical-align: top; background-color: white;">
          <td class="hierarchy" style="vertical-align: top; text-align : left; background-color: white; border: 0px #F0F0F0 solid;
           padding:0px 4px 0px 4px; white-space: nowrap; background-image: url(data: image/png;base64,iVBORw0KG
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          sPVYVAgIJrA/sAAAAASUVORK5CYII=)">
            <img alt="." class="hierarchy" src="data: image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAEAAAAWCAYAAAABxvaqAAAACXBIWXMAAAsTAAALEwEAmpwYAAAAB
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            FEhIdcAYJdYASFRUQhQkLCwkOFwcdEBAXhVabE52ecDahKy0oIQA7" style="background-color: white; background-color: inherit" title="Element"/>  
            <a href="references-definitions.html#Reference" title="Reference : A reference from one resource to another.">Reference</a> 
            <a name="Reference"> </a> 
          </td> 
          <td class="hierarchy" style="vertical-align: top; text-align : left; background-color: white; border: 0px #F0F0F0 solid;
           padding:0px 4px 0px 4px">
            <span style="padding: 3px" title="This element is included in summaries">Σ</span> 
            <span style="padding: 3px" title="This element has or is affected by some invariants">I</span> 
          </td> 
          <td class="hierarchy" style="vertical-align: top; text-align : left; background-color: white; border: 0px #F0F0F0 solid;
           padding:0px 4px 0px 4px"/> 
          <td class="hierarchy" style="vertical-align: top; text-align : left; background-color: white; border: 0px #F0F0F0 solid;
           padding:0px 4px 0px 4px">
            <a href="element.html">Element</a> 
          </td> 
          <td class="hierarchy" style="vertical-align: top; text-align : left; background-color: white; border: 0px #F0F0F0 solid;
           padding:0px 4px 0px 4px">A reference from one resource to another
            <br/>  
            <span style="font-style: italic" title="ref-1">+ SHALL have a contained resource if a local reference is provided</span> 
            <br/>  Elements defined in Ancestors: 
            <a href="element.html#Element" title="unique id for the element within a resource (for internal references). This may be any
             string value that does not contain spaces.">id</a> , 
            <a href="element.html#Element" title="May be used to represent additional information that is not part of the basic definition
             of the element. In order to make the use of extensions safe and manageable, there is a
             strict set of governance  applied to the definition and use of extensions. Though any
             implementer is allowed to define an extension, there is a set of requirements that SHALL
             be met as part of the definition of the extension.">extension</a> 
          </td> 
        </tr> 

        <tr style="border: 0px #F0F0F0 solid; padding:0px; vertical-align: top; background-color: white;">
          <td class="hierarchy" style="vertical-align: top; text-align : left; background-color: white; border: 0px #F0F0F0 solid;
           padding:0px 4px 0px 4px; white-space: nowrap; background-image: url(data: image/png;base64,iVBORw0KG
          goAAAANSUhEUgAAAyAAAAACCAYAAACg/LjIAAAAL0lEQVR42u3XsQ0AQAgCQHdl/xn8jxvYWB3JlTR0VJLa+OltBwAAYP6EEQAAgC
          sPVYVAgIJrA/sAAAAASUVORK5CYII=)">
            <img alt="." class="hierarchy" src="data: image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAEAAAAWCAYAAAABxvaqAAAACXBIWXMAAAsTAAALEwEAmpwYAAAAB
            3RJTUUH3wYeFzIs1vtcMQAAAB1pVFh0Q29tbWVudAAAAAAAQ3JlYXRlZCB3aXRoIEdJTVBkLmUHAAAAE0lEQVQI12P4//8/AxMDAw
            NdCABMPwMo2ctnoQAAAABJRU5ErkJggg==" style="background-color: inherit"/> 
            <img alt="." class="hierarchy" src="data: image/png;base64,iVBORw0KGgoAAAANSUhEUgAAABAAAAAWCAYAAADJqhx8AAAACXBIWXMAAAsTAAALEwEAmpwYAAAAB
            3RJTUUH3wYeFzI3XJ6V3QAAAB1pVFh0Q29tbWVudAAAAAAAQ3JlYXRlZCB3aXRoIEdJTVBkLmUHAAAANklEQVQ4y+2RsQ0AIAzDav
            7/2VzQwoCY4iWbZSmo1QGoUgNMghvWaIejPQW/CrrNCylIwcOCDYfLNRcNer4SAAAAAElFTkSuQmCC" style="background-color: inherit"/> 
            <img alt="." class="hierarchy" src="data: image/png;base64,iVBORw0KGgoAAAANSUhEUgAAABAAAAAQCAYAAAAf8/9hAAAABmJLR0QA/wD/AP+gvaeTAAAACXBIW
            XMAAAsTAAALEwEAmpwYAAAAB3RJTUUH3gYBFzI0BrFQCwAAAERJREFUOMtj/P//PwMlgImBQjDwBrCcOnWKokBgYWBgYDCU+06W5i
            8MUggvnH/EOVJjAW4AuQHJ+O75LYqikXE0LzAAALePEntTkEoSAAAAAElFTkSuQmCC" style="background-color: white; background-color: inherit" title="Primitive Data Type"/>  
            <a href="references-definitions.html#Reference.reference" title="Reference.reference : A reference to a location at which the other resource is found.
             The reference may be a relative reference, in which case it is relative to the service
             base URL, or an absolute URL that resolves to the location where the resource is found.
             The reference may be version specific or not. If the reference is not to a FHIR RESTful
             server, then it should be assumed to be version specific. Internal fragment references
             (start with '#') refer to contained resources.">reference</a> 
            <a name="Reference.reference"> </a> 
          </td> 
          <td class="hierarchy" style="vertical-align: top; text-align : left; background-color: white; border: 0px #F0F0F0 solid;
           padding:0px 4px 0px 4px">
            <span style="padding: 3px" title="This element is included in summaries">Σ</span> 
            <span style="padding: 3px" title="This element has or is affected by some invariants">I</span> 
          </td> 
          <td class="hierarchy" style="vertical-align: top; text-align : left; background-color: white; border: 0px #F0F0F0 solid;
           padding:0px 4px 0px 4px">0..1</td> 
          <td class="hierarchy" style="vertical-align: top; text-align : left; background-color: white; border: 0px #F0F0F0 solid;
           padding:0px 4px 0px 4px">
            <a href="datatypes.html#string">string</a> 
          </td> 
          <td class="hierarchy" style="vertical-align: top; text-align : left; background-color: white; border: 0px #F0F0F0 solid;
           padding:0px 4px 0px 4px">Literal reference, Relative, internal or absolute URL</td> 
        </tr> 

        <tr style="border: 0px #F0F0F0 solid; padding:0px; vertical-align: top; background-color: white;">
          <td class="hierarchy" style="vertical-align: top; text-align : left; background-color: white; border: 0px #F0F0F0 solid;
           padding:0px 4px 0px 4px; white-space: nowrap; background-image: url(data: image/png;base64,iVBORw0KG
          goAAAANSUhEUgAAAyAAAAACCAYAAACg/LjIAAAAL0lEQVR42u3XsQ0AQAgCQHdl/xn8jxvYWB3JlTR0VJLa+OltBwAAYP6EEQAAgC
          sPVYVAgIJrA/sAAAAASUVORK5CYII=)">
            <img alt="." class="hierarchy" src="data: image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAEAAAAWCAYAAAABxvaqAAAACXBIWXMAAAsTAAALEwEAmpwYAAAAB
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            NdCABMPwMo2ctnoQAAAABJRU5ErkJggg==" style="background-color: inherit"/> 
            <img alt="." class="hierarchy" src="data: image/png;base64,iVBORw0KGgoAAAANSUhEUgAAABAAAAAWCAYAAADJqhx8AAAACXBIWXMAAAsTAAALEwEAmpwYAAAAB
            3RJTUUH3wYeFzI3XJ6V3QAAAB1pVFh0Q29tbWVudAAAAAAAQ3JlYXRlZCB3aXRoIEdJTVBkLmUHAAAANklEQVQ4y+2RsQ0AIAzDav
            7/2VzQwoCY4iWbZSmo1QGoUgNMghvWaIejPQW/CrrNCylIwcOCDYfLNRcNer4SAAAAAElFTkSuQmCC" style="background-color: inherit"/> 
            <img alt="." class="hierarchy" src="data: image/png;base64,R0lGODlhEAAQAOZ/APrkusOiYvvfqbiXWaV2G+jGhdq1b8GgYf3v1frw3vTUlsWkZNewbcSjY/DQk
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            UPvowat8Ivvgq/Pbrvzgq/PguvrgrqN0Gda2evfYm9+7d/rpw9q6e/LSku/Rl/XVl/LSlfrkt+zVqe7Wqv3x1/bNffbOf59wFdS6i
            f3u0vrqyP3owPvepfXQivDQkO/PkKh9K7STVf779P///////yH5BAEAAH8ALAAAAAAQABAAAAfNgH+Cg36FfoOIhH4JBxBghYl/hQ
            kNAV0IVT5GkJKLCwtQaSsSdx9aR26Gcwt2IkQaNRI6dBERIzCFDSgWSW8WCDkbBnoOQ3uFARc/JQJfCAZlT0x4ZFyFBxdNQT9ZCBN
            WKQoKUQ+FEDgcdTIAV14YDmg2CgSFA0hmQC5TLE4VRTdrKJAoxOeFCzZSwsw4U6BCizwUQhQyEaAPiAwCVNCY0FCNnA6GPAwYoETI
            FgY9loiRA4dToTYnsOxg8CBGHE6ICvEYQ4AKzkidfgoKBAA7" style="background-color: white; background-color: inherit" title="Data Type"/>  
            <a href="references-definitions.html#Reference.identifier" title="Reference.identifier : An identifier for the other resource. This is used when there is
             no way to reference the other resource directly, either because the entity is not available
             through a FHIR server, or because there is no way for the author of the resource to convert
             a known identifier to an actual location. There is no requirement that a Reference.identifier
             point to something that is actually exposed as a FHIR instance, but it SHALL point to
             a business concept that would be expected to be exposed as a FHIR instance, and that instance
             would need to be of a FHIR resource type allowed by the reference.">identifier</a> 
            <a name="Reference.identifier"> </a> 
          </td> 
          <td class="hierarchy" style="vertical-align: top; text-align : left; background-color: white; border: 0px #F0F0F0 solid;
           padding:0px 4px 0px 4px">
            <span style="padding: 3px" title="This element is included in summaries">Σ</span> 
          </td> 
          <td class="hierarchy" style="vertical-align: top; text-align : left; background-color: white; border: 0px #F0F0F0 solid;
           padding:0px 4px 0px 4px">0..1</td> 
          <td class="hierarchy" style="vertical-align: top; text-align : left; background-color: white; border: 0px #F0F0F0 solid;
           padding:0px 4px 0px 4px">
            <a href="datatypes.html#Identifier">Identifier</a> 
          </td> 
          <td class="hierarchy" style="vertical-align: top; text-align : left; background-color: white; border: 0px #F0F0F0 solid;
           padding:0px 4px 0px 4px">Logical reference, when literal reference is not known</td> 
        </tr> 

        <tr style="border: 0px #F0F0F0 solid; padding:0px; vertical-align: top; background-color: white;">
          <td class="hierarchy" style="vertical-align: top; text-align : left; background-color: white; border: 0px #F0F0F0 solid;
           padding:0px 4px 0px 4px; white-space: nowrap; background-image: url(data: image/png;base64,iVBORw0KG
          goAAAANSUhEUgAAAyAAAAACCAYAAACg/LjIAAAAI0lEQVR42u3QIQEAAAACIL/6/4MvTAQOkLYBAAB4kAAAANwMad9AqkRjgNAAAA
          AASUVORK5CYII=)">
            <img alt="." class="hierarchy" src="data: image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAEAAAAWCAYAAAABxvaqAAAACXBIWXMAAAsTAAALEwEAmpwYAAAAB
            3RJTUUH3wYeFzIs1vtcMQAAAB1pVFh0Q29tbWVudAAAAAAAQ3JlYXRlZCB3aXRoIEdJTVBkLmUHAAAAE0lEQVQI12P4//8/AxMDAw
            NdCABMPwMo2ctnoQAAAABJRU5ErkJggg==" style="background-color: inherit"/> 
            <img alt="." class="hierarchy" src="data: image/png;base64,iVBORw0KGgoAAAANSUhEUgAAABAAAAAWCAYAAADJqhx8AAAACXBIWXMAAAsTAAALEwEAmpwYAAAAB
            3RJTUUH3wYeFzME+lXFigAAAB1pVFh0Q29tbWVudAAAAAAAQ3JlYXRlZCB3aXRoIEdJTVBkLmUHAAAANklEQVQ4y+3OsRUAIAjEUO
            L+O8cJABttJM11/x1qZAGqRBEVcNIqdWj1efDqQbb3HwwwwEfABmQUHSPM9dtDAAAAAElFTkSuQmCC" style="background-color: inherit"/> 
            <img alt="." class="hierarchy" src="data: image/png;base64,iVBORw0KGgoAAAANSUhEUgAAABAAAAAQCAYAAAAf8/9hAAAABmJLR0QA/wD/AP+gvaeTAAAACXBIW
            XMAAAsTAAALEwEAmpwYAAAAB3RJTUUH3gYBFzI0BrFQCwAAAERJREFUOMtj/P//PwMlgImBQjDwBrCcOnWKokBgYWBgYDCU+06W5i
            8MUggvnH/EOVJjAW4AuQHJ+O75LYqikXE0LzAAALePEntTkEoSAAAAAElFTkSuQmCC" style="background-color: white; background-color: inherit" title="Primitive Data Type"/>  
            <a href="references-definitions.html#Reference.display" title="Reference.display : Plain text narrative that identifies the resource in addition to the
             resource reference.">display</a> 
            <a name="Reference.display"> </a> 
          </td> 
          <td class="hierarchy" style="vertical-align: top; text-align : left; background-color: white; border: 0px #F0F0F0 solid;
           padding:0px 4px 0px 4px">
            <span style="padding: 3px" title="This element is included in summaries">Σ</span> 
          </td> 
          <td class="hierarchy" style="vertical-align: top; text-align : left; background-color: white; border: 0px #F0F0F0 solid;
           padding:0px 4px 0px 4px">0..1</td> 
          <td class="hierarchy" style="vertical-align: top; text-align : left; background-color: white; border: 0px #F0F0F0 solid;
           padding:0px 4px 0px 4px">
            <a href="datatypes.html#string">string</a> 
          </td> 
          <td class="hierarchy" style="vertical-align: top; text-align : left; background-color: white; border: 0px #F0F0F0 solid;
           padding:0px 4px 0px 4px">Text alternative for the resource</td> 
        </tr> 

        <tr> 
          <td class="hierarchy" colspan="5">
            <br/>  
            <a href="formats.html#table" title="Legend for this format">
              <img alt="doco" src="help16.png" style="background-color: inherit"/>  Documentation for this format
            </a> 
          </td> 
        </tr> 
      </table> 
    </div> 
  </text> 
  <url value="http://hl7.org/fhir/StructureDefinition/Reference"/> 
  <name value="Reference"/> 
  <status value="draft"/> 
  <date value="2019-10-24T11:53:00+11:00"/> 
  <publisher value="HL7 FHIR Standard"/> 
  <contact> 
    <telecom> 
      <system value="url"/> 
      <value value="http://hl7.org/fhir"/> 
    </telecom> 
  </contact> 
  <description value="Base StructureDefinition for Reference Type"/> 
  <fhirVersion value="3.0.2"/> 
  <mapping> 
    <identity value="rim"/> 
    <uri value="http://hl7.org/v3"/> 
    <name value="RIM Mapping"/> 
  </mapping> 
  <kind value="complex-type"/> 
  <abstract value="false"/> 
  <type value="Reference"/> 
  <baseDefinition value="http://hl7.org/fhir/StructureDefinition/Element"/> 
  <derivation value="specialization"/> 
  <snapshot> 
    <element id="Reference">
      <path value="Reference"/> 
      <short value="A reference from one resource to another"/> 
      <definition value="A reference from one resource to another."/> 
      <comment value="References SHALL be a reference to an actual FHIR resource, and SHALL be resolveable (allowing
       for access control, temporary unavailability, etc). Resolution can be either by retrieval
       from the URL, or, where applicable by resource type, by treating an absolute reference
       as a canonical URL and looking it up in a local registry/repository."/> 
      <min value="0"/> 
      <max value="*"/> 
      <condition value="ele-1"/> 
      <constraint> 
        <key value="ele-1"/> 
        <severity value="error"/> 
        <human value="All FHIR elements must have a @value or children"/> 
        <expression value="hasValue() | (children().count() &gt; id.count())"/> 
        <xpath value="@value|f:*|h:div"/> 
        <source value="Element"/> 
      </constraint> 
      <constraint> 
        <key value="ref-1"/> 
        <severity value="error"/> 
        <human value="SHALL have a contained resource if a local reference is provided"/> 
        <expression value="reference.startsWith('#').not() or (reference.substring(1).trace('url') in %resource.contained.id.tr
        ace('ids'))"/> 
        <xpath value="not(starts-with(f:reference/@value, '#')) or exists(ancestor::*[self::f:entry or self::f:parameter]/
        f:resource/f:*/f:contained/f:*[f:id/@value=substring-after(current()/f:reference/@value,
         '#')]|/*/f:contained/f:*[f:id/@value=substring-after(current()/f:reference/@value, '#')])"/> 
      </constraint> 
      <mapping> 
        <identity value="rim"/> 
        <map value="n/a"/> 
      </mapping> 
      <mapping> 
        <identity value="rim"/> 
        <map value="The target of a resource reference is a RIM entry point (Act, Role, or Entity)"/> 
      </mapping> 
    </element> 
    <element id="Reference.id">
      <path value="Reference.id"/> 
      <representation value="xmlAttr"/> 
      <short value="xml:id (or equivalent in JSON)"/> 
      <definition value="unique id for the element within a resource (for internal references). This may be any
       string value that does not contain spaces."/> 
      <min value="0"/> 
      <max value="1"/> 
      <base> 
        <path value="Element.id"/> 
        <min value="0"/> 
        <max value="1"/> 
      </base> 
      <type> 
        <code value="string"/> 
      </type> 
      <mapping> 
        <identity value="rim"/> 
        <map value="n/a"/> 
      </mapping> 
    </element> 
    <element id="Reference.extension">
      <path value="Reference.extension"/> 
      <slicing> 
        <discriminator> 
          <type value="value"/> 
          <path value="url"/> 
        </discriminator> 
        <description value="Extensions are always sliced by (at least) url"/> 
        <rules value="open"/> 
      </slicing> 
      <short value="Additional Content defined by implementations"/> 
      <definition value="May be used to represent additional information that is not part of the basic definition
       of the element. In order to make the use of extensions safe and manageable, there is a
       strict set of governance  applied to the definition and use of extensions. Though any
       implementer is allowed to define an extension, there is a set of requirements that SHALL
       be met as part of the definition of the extension."/> 
      <comment value="There can be no stigma associated with the use of extensions by any application, project,
       or standard - regardless of the institution or jurisdiction that uses or defines the extensions.
        The use of extensions is what allows the FHIR specification to retain a core level of
       simplicity for everyone."/> 
      <alias value="extensions"/> 
      <alias value="user content"/> 
      <min value="0"/> 
      <max value="*"/> 
      <base> 
        <path value="Element.extension"/> 
        <min value="0"/> 
        <max value="*"/> 
      </base> 
      <type> 
        <code value="Extension"/> 
      </type> 
      <mapping> 
        <identity value="rim"/> 
        <map value="n/a"/> 
      </mapping> 
    </element> 
    <element id="Reference.reference">
      <path value="Reference.reference"/> 
      <short value="Literal reference, Relative, internal or absolute URL"/> 
      <definition value="A reference to a location at which the other resource is found. The reference may be a
       relative reference, in which case it is relative to the service base URL, or an absolute
       URL that resolves to the location where the resource is found. The reference may be version
       specific or not. If the reference is not to a FHIR RESTful server, then it should be assumed
       to be version specific. Internal fragment references (start with '#') refer to contained
       resources."/> 
      <comment value="Using absolute URLs provides a stable scalable approach suitable for a cloud/web context,
       while using relative/logical references provides a flexible approach suitable for use
       when trading across closed eco-system boundaries.   Absolute URLs do not need to point
       to a FHIR RESTful server, though this is the preferred approach. If the URL conforms to
       the structure &quot;/[type]/[id]&quot; then it should be assumed that the reference is
       to a FHIR RESTful server."/> 
      <min value="0"/> 
      <max value="1"/> 
      <type> 
        <code value="string"/> 
      </type> 
      <condition value="ref-1"/> 
      <isSummary value="true"/> 
      <mapping> 
        <identity value="rim"/> 
        <map value="N/A"/> 
      </mapping> 
    </element> 
    <element id="Reference.identifier">
      <path value="Reference.identifier"/> 
      <short value="Logical reference, when literal reference is not known"/> 
      <definition value="An identifier for the other resource. This is used when there is no way to reference the
       other resource directly, either because the entity is not available through a FHIR server,
       or because there is no way for the author of the resource to convert a known identifier
       to an actual location. There is no requirement that a Reference.identifier point to something
       that is actually exposed as a FHIR instance, but it SHALL point to a business concept
       that would be expected to be exposed as a FHIR instance, and that instance would need
       to be of a FHIR resource type allowed by the reference."/> 
      <comment value="When an identifier is provided in place of a reference, any system processing the reference
       will only be able to resolve the identifier to a reference if it understands the business
       context in which the identifier is used. Sometimes this is global (e.g. a national identifier)
       but often it is not. For this reason, none of the useful mechanisms described for working
       with references (e.g. chaining, includes) are possible, nor should servers be expected
       to be able resolve the reference. Servers may accept an identifier based reference untouched,
       resolve it, and/or reject it - see CapabilityStatement.rest.resource.referencePolicy.
       

When both an identifier and a literal reference are provided, the literal reference is
       preferred. Applications processing the resource are allowed - but not required - to check
       that the identifier matches the literal reference

Applications converting a logical reference to a literal reference may choose to leave
       the logical reference present, or remove it."/> 
      <min value="0"/> 
      <max value="1"/> 
      <type> 
        <code value="Identifier"/> 
      </type> 
      <isSummary value="true"/> 
      <mapping> 
        <identity value="rim"/> 
        <map value=".identifier"/> 
      </mapping> 
    </element> 
    <element id="Reference.display">
      <extension url="http://hl7.org/fhir/StructureDefinition/elementdefinition-translatable">
        <valueBoolean value="true"/> 
      </extension> 
      <path value="Reference.display"/> 
      <short value="Text alternative for the resource"/> 
      <definition value="Plain text narrative that identifies the resource in addition to the resource reference."/> 
      <comment value="This is generally not the same as the Resource.text of the referenced resource.  The purpose
       is to identify what's being referenced, not to fully describe it."/> 
      <min value="0"/> 
      <max value="1"/> 
      <type> 
        <code value="string"/> 
      </type> 
      <isSummary value="true"/> 
      <mapping> 
        <identity value="rim"/> 
        <map value="N/A"/> 
      </mapping> 
    </element> 
  </snapshot> 
  <differential> 
    <element id="Reference">
      <path value="Reference"/> 
      <short value="A reference from one resource to another"/> 
      <definition value="A reference from one resource to another."/> 
      <comment value="References SHALL be a reference to an actual FHIR resource, and SHALL be resolveable (allowing
       for access control, temporary unavailability, etc). Resolution can be either by retrieval
       from the URL, or, where applicable by resource type, by treating an absolute reference
       as a canonical URL and looking it up in a local registry/repository."/> 
      <min value="0"/> 
      <max value="*"/> 
      <constraint> 
        <key value="ref-1"/> 
        <severity value="error"/> 
        <human value="SHALL have a contained resource if a local reference is provided"/> 
        <expression value="reference.startsWith('#').not() or (reference.substring(1).trace('url') in %resource.contained.id.tr
        ace('ids'))"/> 
        <xpath value="not(starts-with(f:reference/@value, '#')) or exists(ancestor::*[self::f:entry or self::f:parameter]/
        f:resource/f:*/f:contained/f:*[f:id/@value=substring-after(current()/f:reference/@value,
         '#')]|/*/f:contained/f:*[f:id/@value=substring-after(current()/f:reference/@value, '#')])"/> 
      </constraint> 
      <mapping> 
        <identity value="rim"/> 
        <map value="The target of a resource reference is a RIM entry point (Act, Role, or Entity)"/> 
      </mapping> 
    </element> 
    <element id="Reference.reference">
      <path value="Reference.reference"/> 
      <short value="Literal reference, Relative, internal or absolute URL"/> 
      <definition value="A reference to a location at which the other resource is found. The reference may be a
       relative reference, in which case it is relative to the service base URL, or an absolute
       URL that resolves to the location where the resource is found. The reference may be version
       specific or not. If the reference is not to a FHIR RESTful server, then it should be assumed
       to be version specific. Internal fragment references (start with '#') refer to contained
       resources."/> 
      <comment value="Using absolute URLs provides a stable scalable approach suitable for a cloud/web context,
       while using relative/logical references provides a flexible approach suitable for use
       when trading across closed eco-system boundaries.   Absolute URLs do not need to point
       to a FHIR RESTful server, though this is the preferred approach. If the URL conforms to
       the structure &quot;/[type]/[id]&quot; then it should be assumed that the reference is
       to a FHIR RESTful server."/> 
      <min value="0"/> 
      <max value="1"/> 
      <type> 
        <code value="string"/> 
      </type> 
      <condition value="ref-1"/> 
      <isSummary value="true"/> 
      <mapping> 
        <identity value="rim"/> 
        <map value="N/A"/> 
      </mapping> 
    </element> 
    <element id="Reference.identifier">
      <path value="Reference.identifier"/> 
      <short value="Logical reference, when literal reference is not known"/> 
      <definition value="An identifier for the other resource. This is used when there is no way to reference the
       other resource directly, either because the entity is not available through a FHIR server,
       or because there is no way for the author of the resource to convert a known identifier
       to an actual location. There is no requirement that a Reference.identifier point to something
       that is actually exposed as a FHIR instance, but it SHALL point to a business concept
       that would be expected to be exposed as a FHIR instance, and that instance would need
       to be of a FHIR resource type allowed by the reference."/> 
      <comment value="When an identifier is provided in place of a reference, any system processing the reference
       will only be able to resolve the identifier to a reference if it understands the business
       context in which the identifier is used. Sometimes this is global (e.g. a national identifier)
       but often it is not. For this reason, none of the useful mechanisms described for working
       with references (e.g. chaining, includes) are possible, nor should servers be expected
       to be able resolve the reference. Servers may accept an identifier based reference untouched,
       resolve it, and/or reject it - see CapabilityStatement.rest.resource.referencePolicy.
       

When both an identifier and a literal reference are provided, the literal reference is
       preferred. Applications processing the resource are allowed - but not required - to check
       that the identifier matches the literal reference

Applications converting a logical reference to a literal reference may choose to leave
       the logical reference present, or remove it."/> 
      <min value="0"/> 
      <max value="1"/> 
      <type> 
        <code value="Identifier"/> 
      </type> 
      <isSummary value="true"/> 
      <mapping> 
        <identity value="rim"/> 
        <map value=".identifier"/> 
      </mapping> 
    </element> 
    <element id="Reference.display">
      <extension url="http://hl7.org/fhir/StructureDefinition/elementdefinition-translatable">
        <valueBoolean value="true"/> 
      </extension> 
      <path value="Reference.display"/> 
      <short value="Text alternative for the resource"/> 
      <definition value="Plain text narrative that identifies the resource in addition to the resource reference."/> 
      <comment value="This is generally not the same as the Resource.text of the referenced resource.  The purpose
       is to identify what's being referenced, not to fully describe it."/> 
      <min value="0"/> 
      <max value="1"/> 
      <type> 
        <code value="string"/> 
      </type> 
      <isSummary value="true"/> 
      <mapping> 
        <identity value="rim"/> 
        <map value="N/A"/> 
      </mapping> 
    </element> 
  </differential> 
</StructureDefinition> 

Usage note: every effort has been made to ensure that the examples are correct and useful, but they are not a normative part of the specification.