HL7.FHIR.UV.EXTENSIONS\Preferred Terminology Server - XML Representation

FHIR Extensions Pack, published by HL7 International / FHIR Infrastructure. This guide is not an authorized publication; it is the continuous build for version 5.2.0-ballot built by the FHIR (HL7® FHIR® Standard) CI Build. This version is based on the current content of https://github.com/HL7/fhir-extensions/ and changes regularly. See the Directory of published versions
Extension: PreferredTerminologyServer - XML Profile

Page standards status: Trial-use
Maturity Level: 4
XML representation of the sdc-questionnaire-preferredTerminologyServer extension.
Raw xml | Download

<StructureDefinition xmlns="http://hl7.org/fhir">
  <id value="sdc-questionnaire-preferredTerminologyServer"/>
  <text>
    <status value="extensions"/>
    <div xmlns="http://www.w3.org/1999/xhtml"><p class="res-header-id"><b>Generated Narrative: StructureDefinition sdc-questionnaire-preferredTerminologyServer</b></p><a name="sdc-questionnaire-preferredTerminologyServer"> </a><a name="hcsdc-questionnaire-preferredTerminologyServer"> </a><a name="sdc-questionnaire-preferredTerminologyServer-en-US"> </a><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 style="vertical-align: top; text-align : left; background-color: white; border: 0px #F0F0F0 solid; padding:0px 4px 0px 4px" class="hierarchy"><a href="https://build.fhir.org/ig/FHIR/ig-guidance/readingIgs.html#table-views" title="The logical name of the element">Name</a></th><th style="vertical-align: top; text-align : left; background-color: white; border: 0px #F0F0F0 solid; padding:0px 4px 0px 4px" class="hierarchy"><a href="https://build.fhir.org/ig/FHIR/ig-guidance/readingIgs.html#table-views" title="Information about the use of the element">Flags</a></th><th style="vertical-align: top; text-align : left; background-color: white; border: 0px #F0F0F0 solid; padding:0px 4px 0px 4px" class="hierarchy"><a href="https://build.fhir.org/ig/FHIR/ig-guidance/readingIgs.html#table-views" title="Minimum and Maximum # of times the element can appear in the instance">Card.</a></th><th style="width: 100px" class="hierarchy"><a href="https://build.fhir.org/ig/FHIR/ig-guidance/readingIgs.html#table-views" title="Reference to the type of the element">Type</a></th><th style="vertical-align: top; text-align : left; background-color: white; border: 0px #F0F0F0 solid; padding:0px 4px 0px 4px" class="hierarchy"><a href="https://build.fhir.org/ig/FHIR/ig-guidance/readingIgs.html#table-views" title="Additional information about the element">Description &amp; Constraints</a><span style="float: right"><a href="https://build.fhir.org/ig/FHIR/ig-guidance/readingIgs.html#table-views" title="Legend for this format"><img src="data:image/png;base64,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" alt="doco" style="background-color: inherit"/></a></span></th></tr><tr style="border: 0px #F0F0F0 solid; padding:0px; vertical-align: top; background-color: white"><td 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(tbl_bck1.png)" class="hierarchy"><img src="tbl_spacer.png" alt="." style="background-color: inherit" class="hierarchy"/><img src="icon_element.gif" alt="." style="background-color: white; background-color: inherit" title="Element" class="hierarchy"/> <a href="StructureDefinition-sdc-questionnaire-preferredTerminologyServer-definitions.html#Extension" title="Indicates the terminology server(s) that are known to be capable of returning and potentially expanding the value set(s) associated with the resource or a particular portion of the resource (depending on where the extension appears).  If a full URL is not provided AND the requested query is a terminology operation (e.g. $lookup or $expand) the client SHOULD execute the operation against (one of) the preferredTerminologyServer(s) rather than the local repository. Systems SHOULD evaluate value sets using terminology servers as follows:  First, try any terminology servers declared on the element in question.  If there are more then one, try them in the order they appear.  Then try any servers that appear on ancestor elements in order of closest ancestor up to any on the resource root  If there are no declared servers or none of the ones listed provide a useful response, the form filler may then try any of the typical servers it would normally use.  A 'useful response' means a response that provides a valid (though potentially empty) expansion.  Clients MAY wish to log/report errors returned by terminology servers.">Extension</a><a name="Extension"> </a></td><td style="vertical-align: top; text-align : left; background-color: white; border: 0px #F0F0F0 solid; padding:0px 4px 0px 4px" class="hierarchy"/><td style="vertical-align: top; text-align : left; background-color: white; border: 0px #F0F0F0 solid; padding:0px 4px 0px 4px" class="hierarchy"><span style="opacity: 0.5">0</span><span style="opacity: 0.5">..</span><span style="opacity: 0.5">*</span></td><td style="vertical-align: top; text-align : left; background-color: white; border: 0px #F0F0F0 solid; padding:0px 4px 0px 4px" class="hierarchy"><a href="http://hl7.org/fhir/R5/extensibility.html#Extension">Extension</a></td><td style="vertical-align: top; text-align : left; background-color: white; border: 0px #F0F0F0 solid; padding:0px 4px 0px 4px" class="hierarchy">Preferred terminology server</td></tr>
<tr style="border: 0px #F0F0F0 solid; padding:0px; vertical-align: top; background-color: #F7F7F7"><td style="vertical-align: top; text-align : left; background-color: #F7F7F7; border: 0px #F0F0F0 solid; padding:0px 4px 0px 4px; white-space: nowrap; background-image: url(tbl_bck10.png)" class="hierarchy"><img src="tbl_spacer.png" alt="." style="background-color: inherit" class="hierarchy"/><img src="tbl_vjoin.png" alt="." style="background-color: inherit" class="hierarchy"/><img src="icon_extension_simple.png" alt="." style="background-color: #F7F7F7; background-color: inherit" title="Simple Extension" class="hierarchy"/> <span style="text-decoration:line-through">extension</span><a name="Extension.extension"> </a></td><td style="vertical-align: top; text-align : left; background-color: #F7F7F7; border: 0px #F0F0F0 solid; padding:0px 4px 0px 4px" class="hierarchy"/><td style="vertical-align: top; text-align : left; background-color: #F7F7F7; border: 0px #F0F0F0 solid; padding:0px 4px 0px 4px" class="hierarchy"><span style="text-decoration:line-through"/><span style="text-decoration:line-through">0</span><span style="text-decoration:line-through">..</span><span style="text-decoration:line-through">0</span></td><td style="vertical-align: top; text-align : left; background-color: #F7F7F7; border: 0px #F0F0F0 solid; padding:0px 4px 0px 4px" class="hierarchy"/><td style="vertical-align: top; text-align : left; background-color: #F7F7F7; border: 0px #F0F0F0 solid; padding:0px 4px 0px 4px" class="hierarchy"/></tr>
<tr style="border: 0px #F0F0F0 solid; padding:0px; vertical-align: top; background-color: white"><td 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(tbl_bck10.png)" class="hierarchy"><img src="tbl_spacer.png" alt="." style="background-color: inherit" class="hierarchy"/><img src="tbl_vjoin.png" alt="." style="background-color: inherit" class="hierarchy"/><img src="icon_element.gif" alt="." style="background-color: white; background-color: inherit" title="Element" class="hierarchy"/> <a href="StructureDefinition-sdc-questionnaire-preferredTerminologyServer-definitions.html#Extension.url">url</a><a name="Extension.url"> </a></td><td style="vertical-align: top; text-align : left; background-color: white; border: 0px #F0F0F0 solid; padding:0px 4px 0px 4px" class="hierarchy"/><td style="vertical-align: top; text-align : left; background-color: white; border: 0px #F0F0F0 solid; padding:0px 4px 0px 4px" class="hierarchy"><span style="opacity: 0.5">1</span><span style="opacity: 0.5">..</span><span style="opacity: 0.5">1</span></td><td style="vertical-align: top; text-align : left; background-color: white; border: 0px #F0F0F0 solid; padding:0px 4px 0px 4px" class="hierarchy"><a style="opacity: 0.5" href="http://hl7.org/fhir/R5/datatypes.html#uri">uri</a></td><td style="vertical-align: top; text-align : left; background-color: white; border: 0px #F0F0F0 solid; padding:0px 4px 0px 4px" class="hierarchy"><span style="color: darkgreen">&quot;http://hl7.org/fhir/StructureDefinition/preferredTerminologyServer&quot;</span></td></tr>
<tr style="border: 0px #F0F0F0 solid; padding:0px; vertical-align: top; background-color: #F7F7F7"><td style="vertical-align: top; text-align : left; background-color: #F7F7F7; border: 0px #F0F0F0 solid; padding:0px 4px 0px 4px; white-space: nowrap; background-image: url(tbl_bck00.png)" class="hierarchy"><img src="tbl_spacer.png" alt="." style="background-color: inherit" class="hierarchy"/><img src="tbl_vjoin_end.png" alt="." style="background-color: inherit" class="hierarchy"/><img src="icon_primitive.png" alt="." style="background-color: #F7F7F7; background-color: inherit" title="Primitive Data Type" class="hierarchy"/> <a href="StructureDefinition-sdc-questionnaire-preferredTerminologyServer-definitions.html#Extension.value[x]">value[x]</a><a name="Extension.value_x_"> </a></td><td style="vertical-align: top; text-align : left; background-color: #F7F7F7; border: 0px #F0F0F0 solid; padding:0px 4px 0px 4px" class="hierarchy"/><td style="vertical-align: top; text-align : left; background-color: #F7F7F7; border: 0px #F0F0F0 solid; padding:0px 4px 0px 4px" class="hierarchy"><span style="opacity: 0.5">0</span><span style="opacity: 0.5">..</span><span style="opacity: 0.5">1</span></td><td style="vertical-align: top; text-align : left; background-color: #F7F7F7; border: 0px #F0F0F0 solid; padding:0px 4px 0px 4px" class="hierarchy"><a href="http://hl7.org/fhir/R5/datatypes.html#url">url</a></td><td style="vertical-align: top; text-align : left; background-color: #F7F7F7; border: 0px #F0F0F0 solid; padding:0px 4px 0px 4px" class="hierarchy"><span style="opacity: 0.5">Value of extension</span></td></tr>
<tr><td colspan="5" class="hierarchy"><br/><a href="https://build.fhir.org/ig/FHIR/ig-guidance/readingIgs.html#table-views" title="Legend for this format"><img src="data:image/png;base64,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" alt="doco" style="background-color: inherit"/> Documentation for this format</a></td></tr></table></div>
  </text>
  <extension
             url="http://hl7.org/fhir/StructureDefinition/structuredefinition-wg">
    <valueCode value="fhir"/>
  </extension>
  <extension
             url="http://hl7.org/fhir/StructureDefinition/structuredefinition-fmm">
    <valueInteger value="4">
      <extension
                 url="http://hl7.org/fhir/StructureDefinition/structuredefinition-conformance-derivedFrom">
        <valueCanonical
                        value="http://hl7.org/fhir/uv/sdc/ImplementationGuide/hl7.fhir.uv.sdc"/>
      </extension>
    </valueInteger>
  </extension>
  <extension
             url="http://hl7.org/fhir/StructureDefinition/structuredefinition-standards-status">
    <valueCode value="trial-use"/>
  </extension>
  <extension
             url="http://hl7.org/fhir/StructureDefinition/structuredefinition-type-characteristics">
    <valueCode value="can-bind"/>
  </extension>
  <url
       value="http://hl7.org/fhir/StructureDefinition/preferredTerminologyServer"/>
  <version value="5.2.0-ballot"/>
  <name value="PreferredTerminologyServer"/>
  <title value="Preferred Terminology Server"/>
  <status value="active"/>
  <date value="2024-12-16T04:47:21+00:00"/>
  <publisher value="HL7 International / FHIR Infrastructure"/>
  <contact>
    <name value="HL7 International / FHIR Infrastructure"/>
    <telecom>
      <system value="url"/>
      <value value="http://www.hl7.org/Special/committees/fiwg"/>
    </telecom>
  </contact>
  <description
               value="Indicates the terminology server(s) that are known to be capable of returning and potentially expanding the value set(s) associated with the resource or a particular portion of the resource (depending on where the extension appears).  If a full URL is not provided AND the requested query is a terminology operation (e.g. $lookup or $expand) the client SHOULD execute the operation against (one of) the preferredTerminologyServer(s) rather than the local repository. Systems SHOULD evaluate value sets using terminology servers as follows:  First, try any terminology servers declared on the element in question.  If there are more then one, try them in the order they appear.  Then try any servers that appear on ancestor elements in order of closest ancestor up to any on the resource root  If there are no declared servers or none of the ones listed provide a useful response, the form filler may then try any of the typical servers it would normally use.  A 'useful response' means a response that provides a valid (though potentially empty) expansion.  Clients MAY wish to log/report errors returned by terminology servers."/>
  <jurisdiction>
    <coding>
      <system value="http://unstats.un.org/unsd/methods/m49/m49.htm"/>
      <code value="001"/>
    </coding>
  </jurisdiction>
  <purpose
           value="Not all terminology servers will necessarily have access to the codes.  If a questionnaire points to value sets, the rendering engine needs to know where to get a current expansion."/>
  <fhirVersion value="5.0.0"/>
  <mapping>
    <identity value="rim"/>
    <uri value="http://hl7.org/v3"/>
    <name value="RIM Mapping"/>
  </mapping>
  <kind value="complex-type"/>
  <abstract value="false"/>
  <context>
    <type value="element"/>
    <expression value="Questionnaire"/>
  </context>
  <context>
    <type value="element"/>
    <expression value="Questionnaire.item"/>
  </context>
  <context>
    <type value="element"/>
    <expression value="ElementDefinition"/>
  </context>
  <type value="Extension"/>
  <baseDefinition value="http://hl7.org/fhir/StructureDefinition/Extension"/>
  <derivation value="constraint"/>
  <snapshot>
    <element id="Extension">
      <path value="Extension"/>
      <short value="Preferred terminology server"/>
      <definition
                  value="Indicates the terminology server(s) that are known to be capable of returning and potentially expanding the value set(s) associated with the resource or a particular portion of the resource (depending on where the extension appears).  If a full URL is not provided AND the requested query is a terminology operation (e.g. $lookup or $expand) the client SHOULD execute the operation against (one of) the preferredTerminologyServer(s) rather than the local repository. Systems SHOULD evaluate value sets using terminology servers as follows:  First, try any terminology servers declared on the element in question.  If there are more then one, try them in the order they appear.  Then try any servers that appear on ancestor elements in order of closest ancestor up to any on the resource root  If there are no declared servers or none of the ones listed provide a useful response, the form filler may then try any of the typical servers it would normally use.  A 'useful response' means a response that provides a valid (though potentially empty) expansion.  Clients MAY wish to log/report errors returned by terminology servers."/>
      <min value="0"/>
      <max value="*"/>
      <base>
        <path value="Extension"/>
        <min value="0"/>
        <max value="*"/>
      </base>
      <constraint>
        <key value="ele-1"/>
        <severity value="error"/>
        <human value="All FHIR elements must have a @value or children"/>
        <expression
                    value="hasValue() or (children().count() &gt; id.count())"/>
        <source value="http://hl7.org/fhir/StructureDefinition/Element"/>
      </constraint>
      <constraint>
        <key value="ext-1"/>
        <severity value="error"/>
        <human value="Must have either extensions or value[x], not both"/>
        <expression value="extension.exists() != value.exists()"/>
        <source value="http://hl7.org/fhir/StructureDefinition/Extension"/>
      </constraint>
      <isModifier value="false"/>
    </element>
    <element id="Extension.id">
      <path value="Extension.id"/>
      <representation value="xmlAttr"/>
      <short value="Unique id for inter-element referencing"/>
      <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>
        <extension
                   url="http://hl7.org/fhir/StructureDefinition/structuredefinition-fhir-type">
          <valueUrl value="id"/>
        </extension>
        <code value="http://hl7.org/fhirpath/System.String"/>
      </type>
      <condition value="ele-1"/>
      <isModifier value="false"/>
      <isSummary value="false"/>
      <mapping>
        <identity value="rim"/>
        <map value="n/a"/>
      </mapping>
    </element>
    <element id="Extension.extension">
      <path value="Extension.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="Extension"/>
      <definition value="An Extension"/>
      <min value="0"/>
      <max value="0"/>
      <base>
        <path value="Element.extension"/>
        <min value="0"/>
        <max value="*"/>
      </base>
      <type>
        <code value="Extension"/>
      </type>
      <constraint>
        <key value="ele-1"/>
        <severity value="error"/>
        <human value="All FHIR elements must have a @value or children"/>
        <expression
                    value="hasValue() or (children().count() &gt; id.count())"/>
        <source value="http://hl7.org/fhir/StructureDefinition/Element"/>
      </constraint>
      <constraint>
        <key value="ext-1"/>
        <severity value="error"/>
        <human value="Must have either extensions or value[x], not both"/>
        <expression value="extension.exists() != value.exists()"/>
        <source value="http://hl7.org/fhir/StructureDefinition/Extension"/>
      </constraint>
      <isModifier value="false"/>
      <isSummary value="false"/>
    </element>
    <element id="Extension.url">
      <path value="Extension.url"/>
      <representation value="xmlAttr"/>
      <short value="identifies the meaning of the extension"/>
      <definition
                  value="Source of the definition for the extension code - a logical name or a URL."/>
      <comment
               value="The definition may point directly to a computable or human-readable definition of the extensibility codes, or it may be a logical URI as declared in some other specification. The definition SHALL be a URI for the Structure Definition defining the extension."/>
      <min value="1"/>
      <max value="1"/>
      <base>
        <path value="Extension.url"/>
        <min value="1"/>
        <max value="1"/>
      </base>
      <type>
        <extension
                   url="http://hl7.org/fhir/StructureDefinition/structuredefinition-fhir-type">
          <valueUrl value="uri"/>
        </extension>
        <code value="http://hl7.org/fhirpath/System.String"/>
      </type>
      <fixedUri
                value="http://hl7.org/fhir/StructureDefinition/preferredTerminologyServer"/>
      <isModifier value="false"/>
      <isSummary value="false"/>
      <mapping>
        <identity value="rim"/>
        <map value="N/A"/>
      </mapping>
    </element>
    <element id="Extension.value[x]">
      <path value="Extension.value[x]"/>
      <short value="Value of extension"/>
      <definition
                  value="Value of extension - must be one of a constrained set of the data types (see [Extensibility](http://hl7.org/fhir/R5/extensibility.html) for a list)."/>
      <min value="0"/>
      <max value="1"/>
      <base>
        <path value="Extension.value[x]"/>
        <min value="0"/>
        <max value="1"/>
      </base>
      <type>
        <code value="url"/>
      </type>
      <condition value="ext-1"/>
      <constraint>
        <key value="ele-1"/>
        <severity value="error"/>
        <human value="All FHIR elements must have a @value or children"/>
        <expression
                    value="hasValue() or (children().count() &gt; id.count())"/>
        <source value="http://hl7.org/fhir/StructureDefinition/Element"/>
      </constraint>
      <isModifier value="false"/>
      <isSummary value="false"/>
      <mapping>
        <identity value="rim"/>
        <map value="N/A"/>
      </mapping>
    </element>
  </snapshot>
  <differential>
    <element id="Extension">
      <path value="Extension"/>
      <short value="Preferred terminology server"/>
      <definition
                  value="Indicates the terminology server(s) that are known to be capable of returning and potentially expanding the value set(s) associated with the resource or a particular portion of the resource (depending on where the extension appears).  If a full URL is not provided AND the requested query is a terminology operation (e.g. $lookup or $expand) the client SHOULD execute the operation against (one of) the preferredTerminologyServer(s) rather than the local repository. Systems SHOULD evaluate value sets using terminology servers as follows:  First, try any terminology servers declared on the element in question.  If there are more then one, try them in the order they appear.  Then try any servers that appear on ancestor elements in order of closest ancestor up to any on the resource root  If there are no declared servers or none of the ones listed provide a useful response, the form filler may then try any of the typical servers it would normally use.  A 'useful response' means a response that provides a valid (though potentially empty) expansion.  Clients MAY wish to log/report errors returned by terminology servers."/>
    </element>
    <element id="Extension.extension">
      <path value="Extension.extension"/>
      <max value="0"/>
    </element>
    <element id="Extension.url">
      <path value="Extension.url"/>
      <fixedUri
                value="http://hl7.org/fhir/StructureDefinition/preferredTerminologyServer"/>
    </element>
    <element id="Extension.value[x]">
      <path value="Extension.value[x]"/>
      <type>
        <code value="url"/>
      </type>
    </element>
  </differential>
</StructureDefinition>