R4 Draft for Comment
FoundationThis page is part of the FHIR Specification (v3.2.0: R4 Ballot 1). 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
| Modeling and Methodology Work Group | Maturity Level: N/A | Ballot Status: Informative |
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 & 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 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,R0lGODlhEAAQAMQfAOvGUf7ztuvPMf/78/fkl/Pbg+u8Rvjqteu2Pf3zxPz36Pz0z+vTmPzurPvuw /npofbjquvNefHVduuyN+uuMu3Oafbgjfnqvf/3zv/3xevPi+vRjP/20/bmsP///////yH5BAEAAB8ALAAAAAAQABAAAAV24CeOZG mepqeqqOgxjBZFa+19r4ftWQUAgqDgltthMshMIJAZ4jYDHsBARSAmFOJvq+g6HIdEFgcYmBWNxoNAsDjGHgBnmV5bCoUDHLBIq9s 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"> <a href="elementdefinition-definitions.html#ElementDefinition.isSummary" style="padding-left: 3px; padding-right: 3px; color: black; background-color: white" title="This element is included in summaries">Σ</a> <a href="conformance-rules.html#constraints" style="padding-left: 3px; padding-right: 3px; color: black; background-color: white" title="This element has or is affected by some invariants">I</a> <a href="versions.html#std-process" style="padding-left: 3px; padding-right: 3px; border: 1px grey solid; font-weight: bold; color: black; background-color: #e6ffe6" title="Ballot Status = Normative">N</a> </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"> <a href="elementdefinition-definitions.html#ElementDefinition.isSummary" style="padding-left: 3px; padding-right: 3px; color: black; background-color: white" title="This element is included in summaries">Σ</a> <a href="conformance-rules.html#constraints" style="padding-left: 3px; padding-right: 3px; color: black; background-color: white" title="This element has or is affected by some invariants">I</a> </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 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,R0lGODlhEAAQAOZ/APrkusOiYvvfqbiXWaV2G+jGhdq1b8GgYf3v1frw3vTUlsWkZNewbcSjY/DQk ad4Hb6dXv3u0f3v1ObEgfPTlerJiP3w1v79+e7OkPrfrfnjuNOtZPrpydaxa+/YrvvdpP779ZxvFPvnwKKBQaFyF/369M2vdaqHRP z58/HNh/vowufFhfroxO3OkPrluv779tK0e6JzGProwvrow9m4eOnIifPTlPDPkP78+Naxaf3v0/zowfXRi+bFhLWUVv379/rnwPv szv3rye3LiPvnv+3MjPDasKiIS/789/3x2f747eXDg+7Mifvu0tu7f+/QkfDTnPXWmPrjsvrjtPbPgrqZW+/QlPz48K2EMv36866O 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 target resource. This is used when there is no way to reference the other resource directly, either because the entity it represents 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"> <a href="elementdefinition-definitions.html#ElementDefinition.isSummary" style="padding-left: 3px; padding-right: 3px; color: black; background-color: white" title="This element is included in summaries">Σ</a> </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"> <a href="elementdefinition-definitions.html#ElementDefinition.isSummary" style="padding-left: 3px; padding-right: 3px; color: black; background-color: white" title="This element is included in summaries">Σ</a> </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="2017-12-20T15:52:34+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: A reference from one resource to another."/> <fhirVersion value="3.2.0"/> <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() > 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 "/[type]/[id]" 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 target resource. This is used when there is no way to reference the other resource directly, either because the entity it represents 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. Reference is intended to point to a structure that can potentially be expressed as a FHIR resource, though there is no need for it to exist as an actual FHIR resource instance - except in as much as an application wishes to actual find the target of the reference. The content referred to be the identifier must meet the logical constraints implied by any limitations on what resource types are permitted for the reference. For example, it would not be legitimate to send the identifier for a drug prescription if the type were Reference(Observation|DiagnosticReport). One of the use-cases for Reference.identifier is the situation where no FHIR representation exists (where the type is Reference (Any)."/> <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 "/[type]/[id]" 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 target resource. This is used when there is no way to reference the other resource directly, either because the entity it represents 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. Reference is intended to point to a structure that can potentially be expressed as a FHIR resource, though there is no need for it to exist as an actual FHIR resource instance - except in as much as an application wishes to actual find the target of the reference. The content referred to be the identifier must meet the logical constraints implied by any limitations on what resource types are permitted for the reference. For example, it would not be legitimate to send the identifier for a drug prescription if the type were Reference(Observation|DiagnosticReport). One of the use-cases for Reference.identifier is the situation where no FHIR representation exists (where the type is Reference (Any)."/> <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.
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