<StructureDefinition xmlns="http://hl7.org/fhir">
  <id value="SearchParameter" />
  <meta>
    <lastUpdated value="2021-01-05T10:01:24.148+11:00" />
  </meta>
  <extension url="http://hl7.org/fhir/StructureDefinition/structuredefinition-category">
    <valueString value="Foundation.Conformance" />
  </extension>
  <extension url="http://hl7.org/fhir/StructureDefinition/structuredefinition-standards-status">
    <valueCode value="trial-use" />
  </extension>
  <extension url="http://hl7.org/fhir/StructureDefinition/structuredefinition-fmm">
    <valueInteger value="3" />
  </extension>
  <extension url="http://hl7.org/fhir/StructureDefinition/structuredefinition-security-category">
    <valueCode value="anonymous" />
  </extension>
  <extension url="http://hl7.org/fhir/StructureDefinition/structuredefinition-wg">
    <valueCode value="fhir" />
  </extension>
  <extension url="http://hl7.org/fhir/build/StructureDefinition/entered-in-error-status">
    <valueCode value=".status = retired" />
  </extension>
  <extension url="http://hl7.org/fhir/build/StructureDefinition/template">
    <valueString value="CanonicalResource" />
  </extension>
  <url value="http://hl7.org/fhir/StructureDefinition/SearchParameter" />
  <version value="4.6.0" />
  <name value="SearchParameter" />
  <status value="draft" />
  <date value="2021-01-05T10:01:24+11:00" />
  <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>
  <description value="A search parameter that defines a named search item that can be used to search/filter on a resource." />
  <fhirVersion value="4.6.0" />
  <mapping>
    <identity value="v2" />
    <uri value="http://hl7.org/v2" />
    <name value="HL7 v2 Mapping" />
  </mapping>
  <mapping>
    <identity value="rim" />
    <uri value="http://hl7.org/v3" />
    <name value="RIM Mapping" />
  </mapping>
  <mapping>
    <identity value="w5" />
    <uri value="http://hl7.org/fhir/fivews" />
    <name value="FiveWs Pattern Mapping" />
  </mapping>
  <mapping>
    <identity value="workflow" />
    <uri value="http://hl7.org/fhir/workflow" />
    <name value="Workflow Pattern" />
  </mapping>
  <mapping>
    <identity value="objimpl" />
    <uri value="http://hl7.org/fhir/object-implementation" />
    <name value="Object Implementation Information" />
  </mapping>
  <kind value="resource" />
  <abstract value="false" />
  <type value="SearchParameter" />
  <baseDefinition value="http://hl7.org/fhir/StructureDefinition/CanonicalResource" />
  <derivation value="specialization" />
  <differential>
    <element id="SearchParameter">
      <extension url="http://hl7.org/fhir/build/StructureDefinition/svg">
        <valueCode value="0,0" />
      </extension>
      <path value="SearchParameter" />
      <short value="Search parameter for a resource" />
      <definition value="A search parameter that defines a named search item that can be used to search/filter on a resource." />
      <comment value="In FHIR, search is not performed directly on a resource (by XML or JSON path), but on a named parameter that maps into the resource content." />
      <min value="0" />
      <max value="*" />
      <constraint>
        <key value="cnl-0" />
        <severity value="warning" />
        <human value="Name should be usable as an identifier for the module by machine processing applications such as code generation" />
        <expression value="name.matches('[A-Z]([A-Za-z0-9_]){0,254}')" />
        <xpath value="not(exists(f:name/@value)) or matches(f:name/@value, '[A-Z]([A-Za-z0-9_]){0,254}')" />
        <source value="http://hl7.org/fhir/StructureDefinition/SearchParameter" />
      </constraint>
      <constraint>
        <key value="spd-1" />
        <severity value="error" />
        <human value="If an xpath is present, there SHALL be an xpathUsage" />
        <expression value="xpath.empty() or xpathUsage.exists()" />
        <xpath value="not(exists(f:xpath)) or exists(f:xpathUsage)" />
        <source value="http://hl7.org/fhir/StructureDefinition/SearchParameter" />
      </constraint>
      <constraint>
        <key value="spd-2" />
        <severity value="error" />
        <human value="Search parameters can only have chain names when the search parameter type is 'reference'" />
        <expression value="chain.empty() or type = 'reference'" />
        <xpath value="not(exists(f:chain)) or (f:type/@value = 'reference')" />
        <source value="http://hl7.org/fhir/StructureDefinition/SearchParameter" />
      </constraint>
      <mapping>
        <identity value="v2" />
        <map value="n/a" />
      </mapping>
      <mapping>
        <identity value="rim" />
        <map value="n/a" />
      </mapping>
      <mapping>
        <identity value="w5" />
        <map value="conformance.behavior" />
      </mapping>
    </element>
    <element id="SearchParameter.url">
      <path value="SearchParameter.url" />
      <short value="Canonical identifier for this search parameter, represented as a URI (globally unique)" />
      <definition value="An absolute URI that is used to identify this search parameter when it is referenced in a specification, model, design or an instance; also called its canonical identifier. This SHOULD be globally unique and SHOULD be a literal address at which at which an authoritative instance of this search parameter is (or will be) published. This URL can be the target of a canonical reference. It SHALL remain the same when the search parameter is stored on different servers." />
      <comment value="Can be a urn:uuid: or a urn:oid: but real http: addresses are preferred.  Multiple instances may share the same URL if they have a distinct version.&#xA;&#xA;The determination of when to create a new version of a resource (same url, new version) vs. defining a new artifact is up to the author.  Considerations for making this decision are found in [Technical and Business Versions](resource.html#versions). &#xA;&#xA;In some cases, the resource can no longer be found at the stated url, but the url itself cannot change. Implementations can use the [meta.source](resource.html#meta) element to indicate where the current master source of the resource can be found." />
      <requirements value="Allows the search parameter to be referenced by a single globally unique identifier. To allow referencing and reusing search parameter definitions under other names on operational systems (in case of name clash)." />
      <min value="1" />
      <max value="1" />
      <type>
        <code value="uri" />
      </type>
      <isSummary value="true" />
      <mapping>
        <identity value="workflow" />
        <map value="Definition.url" />
      </mapping>
      <mapping>
        <identity value="w5" />
        <map value="FiveWs.identifier" />
      </mapping>
    </element>
    <element id="SearchParameter.version">
      <path value="SearchParameter.version" />
      <short value="Business version of the search parameter" />
      <definition value="The identifier that is used to identify this version of the search parameter when it is referenced in a specification, model, design or instance. This is an arbitrary value managed by the search parameter author and is not expected to be globally unique. For example, it might be a timestamp (e.g. yyyymmdd) if a managed version is not available. There is also no expectation that versions can be placed in a lexicographical sequence." />
      <comment value="There may be different search parameter instances that have the same identifier but different versions.  The version can be appended to the url in a reference to allow a reference to a particular business version of the search parameter with the format [url]|[version]." />
      <min value="0" />
      <max value="1" />
      <type>
        <code value="string" />
      </type>
      <isSummary value="true" />
      <mapping>
        <identity value="workflow" />
        <map value="Definition.version" />
      </mapping>
      <mapping>
        <identity value="w5" />
        <map value="FiveWs.version" />
      </mapping>
    </element>
    <element id="SearchParameter.name">
      <path value="SearchParameter.name" />
      <short value="Name for this search parameter (computer friendly)" />
      <definition value="A natural language name identifying the search parameter. This name should be usable as an identifier for the module by machine processing applications such as code generation." />
      <comment value="The name is not expected to be globally unique. The name should be a simple alphanumeric type name to ensure that it is machine-processing friendly." />
      <requirements value="Support human navigation and code generation." />
      <min value="1" />
      <max value="1" />
      <type>
        <code value="string" />
      </type>
      <condition value="cnl-0" />
      <isSummary value="true" />
    </element>
    <element id="SearchParameter.derivedFrom">
      <path value="SearchParameter.derivedFrom" />
      <short value="Original definition for the search parameter" />
      <definition value="Where this search parameter is originally defined. If a derivedFrom is provided, then the details in the search parameter must be consistent with the definition from which it is defined. i.e. the parameter should have the same meaning, and (usually) the functionality should be a proper subset of the underlying search parameter." />
      <comment value="The intent of this is that a server can designate that it provides support for a search parameter defined in the specification itself (e.g.  [`value-quantity`](http://hl7.org/fhir/SearchParameter/Observation-value-quantity), but detail how it is supported by the server." />
      <min value="0" />
      <max value="1" />
      <type>
        <code value="canonical" />
        <targetProfile value="http://hl7.org/fhir/StructureDefinition/SearchParameter" />
      </type>
    </element>
    <element id="SearchParameter.status">
      <path value="SearchParameter.status" />
      <short value="draft | active | retired | unknown" />
      <definition value="The status of this search parameter. Enables tracking the life-cycle of the content." />
      <comment value="Allows filtering of search parameters that are appropriate for use versus not." />
      <min value="1" />
      <max value="1" />
      <type>
        <code value="code" />
      </type>
      <isModifier value="true" />
      <isModifierReason value="This is labeled as &quot;Is Modifier&quot; because applications should not use a retired {{title}} without due consideration" />
      <isSummary value="true" />
      <binding>
        <extension url="http://hl7.org/fhir/StructureDefinition/elementdefinition-bindingName">
          <valueString value="PublicationStatus" />
        </extension>
        <extension url="http://hl7.org/fhir/StructureDefinition/elementdefinition-isCommonBinding">
          <valueBoolean value="true" />
        </extension>
        <strength value="required" />
        <description value="The lifecycle status of an artifact." />
        <valueSet value="http://hl7.org/fhir/ValueSet/publication-status" />
      </binding>
      <mapping>
        <identity value="workflow" />
        <map value="Definition.status" />
      </mapping>
      <mapping>
        <identity value="w5" />
        <map value="FiveWs.status" />
      </mapping>
    </element>
    <element id="SearchParameter.experimental">
      <path value="SearchParameter.experimental" />
      <short value="For testing purposes, not real usage" />
      <definition value="A Boolean value to indicate that this search parameter is authored for testing purposes (or education/evaluation/marketing) and is not intended to be used for genuine usage." />
      <comment value="Allows filtering of search parameters that are appropriate for use versus not." />
      <requirements value="Enables experimental content to be developed following the same lifecycle that would be used for a production-level search parameter." />
      <min value="0" />
      <max value="1" />
      <type>
        <code value="boolean" />
      </type>
      <isSummary value="true" />
      <mapping>
        <identity value="workflow" />
        <map value="Definition.experimental" />
      </mapping>
      <mapping>
        <identity value="w5" />
        <map value="FiveWs.class" />
      </mapping>
    </element>
    <element id="SearchParameter.date">
      <path value="SearchParameter.date" />
      <short value="Date last changed" />
      <definition value="The date  (and optionally time) when the search parameter was published. The date must change when the business version changes and it must change if the status code changes. In addition, it should change when the substantive content of the search parameter changes." />
      <comment value="Note that this is not the same as the resource last-modified-date, since the resource may be a secondary representation of the search parameter. Additional specific dates may be added as extensions or be found by consulting Provenances associated with past versions of the resource." />
      <alias value="Revision Date" />
      <min value="0" />
      <max value="1" />
      <type>
        <code value="dateTime" />
      </type>
      <isSummary value="true" />
      <mapping>
        <identity value="workflow" />
        <map value="Definition.date" />
      </mapping>
      <mapping>
        <identity value="w5" />
        <map value="FiveWs.recorded" />
      </mapping>
    </element>
    <element id="SearchParameter.publisher">
      <path value="SearchParameter.publisher" />
      <short value="Name of the publisher (organization or individual)" />
      <definition value="The name of the organization or individual that published the search parameter." />
      <comment value="Usually an organization but may be an individual. The publisher (or steward) of the search parameter is the organization or individual primarily responsible for the maintenance and upkeep of the search parameter. This is not necessarily the same individual or organization that developed and initially authored the content. The publisher is the primary point of contact for questions or issues with the search parameter. This item SHOULD be populated unless the information is available from context." />
      <requirements value="Helps establish the &quot;authority/credibility&quot; of the search parameter.  May also allow for contact." />
      <min value="0" />
      <max value="1" />
      <type>
        <code value="string" />
      </type>
      <isSummary value="true" />
      <mapping>
        <identity value="workflow" />
        <map value="Definition.publisher" />
      </mapping>
      <mapping>
        <identity value="w5" />
        <map value="FiveWs.witness" />
      </mapping>
    </element>
    <element id="SearchParameter.contact">
      <extension url="http://hl7.org/fhir/build/StructureDefinition/svg">
        <valueCode value="350,60" />
      </extension>
      <path value="SearchParameter.contact" />
      <short value="Contact details for the publisher" />
      <definition value="Contact details to assist a user in finding and communicating with the publisher." />
      <comment value="May be a web site, an email address, a telephone number, etc." />
      <min value="0" />
      <max value="*" />
      <type>
        <code value="ContactDetail" />
      </type>
      <isSummary value="true" />
      <mapping>
        <identity value="workflow" />
        <map value="Definition.contact" />
      </mapping>
    </element>
    <element id="SearchParameter.description">
      <path value="SearchParameter.description" />
      <short value="Natural language description of the search parameter" />
      <definition value="And how it used." />
      <comment value="This description can be used to capture details such as why the search parameter was built, comments about misuse, instructions for clinical use and interpretation, literature references, examples from the paper world, etc. It is not a rendering of the search parameter as conveyed in the 'text' field of the resource itself. This item SHOULD be populated unless the information is available from context (e.g. the language of the search parameter is presumed to be the predominant language in the place the search parameter was created)." />
      <min value="1" />
      <max value="1" />
      <type>
        <code value="markdown" />
      </type>
      <isSummary value="true" />
      <mapping>
        <identity value="workflow" />
        <map value="Definition.description" />
      </mapping>
    </element>
    <element id="SearchParameter.useContext">
      <path value="SearchParameter.useContext" />
      <short value="The context that the content is intended to support" />
      <definition value="The content was developed with a focus and intent of supporting the contexts that are listed. These contexts may be general categories (gender, age, ...) or may be references to specific programs (insurance plans, studies, ...) and may be used to assist with indexing and searching for appropriate search parameter instances." />
      <comment value="When multiple useContexts are specified, there is no expectation that all or any of the contexts apply." />
      <requirements value="Assist in searching for appropriate content." />
      <min value="0" />
      <max value="*" />
      <type>
        <code value="UsageContext" />
      </type>
      <isSummary value="true" />
      <mapping>
        <identity value="workflow" />
        <map value="Definition.useContext" />
      </mapping>
    </element>
    <element id="SearchParameter.jurisdiction">
      <path value="SearchParameter.jurisdiction" />
      <short value="Intended jurisdiction for search parameter (if applicable)" />
      <definition value="A legal or geographic region in which the search parameter is intended to be used." />
      <comment value="It may be possible for the search parameter to be used in jurisdictions other than those for which it was originally designed or intended." />
      <min value="0" />
      <max value="*" />
      <type>
        <code value="CodeableConcept" />
      </type>
      <isSummary value="true" />
      <binding>
        <extension url="http://hl7.org/fhir/StructureDefinition/elementdefinition-bindingName">
          <valueString value="Jurisdiction" />
        </extension>
        <extension url="http://hl7.org/fhir/StructureDefinition/elementdefinition-isCommonBinding">
          <valueBoolean value="true" />
        </extension>
        <strength value="extensible" />
        <description value="Countries and regions within which this artifact is targeted for use." />
        <valueSet value="http://hl7.org/fhir/ValueSet/jurisdiction" />
      </binding>
      <mapping>
        <identity value="workflow" />
        <map value="Definition.jurisdiction" />
      </mapping>
    </element>
    <element id="SearchParameter.purpose">
      <path value="SearchParameter.purpose" />
      <short value="Why this search parameter is defined" />
      <definition value="Explanation of why this search parameter is needed and why it has been designed as it has." />
      <comment value="This element does not describe the usage of the search parameter. Instead, it provides traceability of ''why'' the resource is either needed or ''why'' it is defined as it is.  This may be used to point to source materials or specifications that drove the structure of this search parameter." />
      <min value="0" />
      <max value="1" />
      <type>
        <code value="markdown" />
      </type>
      <mapping>
        <identity value="workflow" />
        <map value="Definition.purpose" />
      </mapping>
      <mapping>
        <identity value="w5" />
        <map value="FiveWs.why[x]" />
      </mapping>
      <mapping>
        <identity value="objimpl" />
        <map value="no-gen-base" />
      </mapping>
    </element>
    <element id="SearchParameter.code">
      <extension url="http://hl7.org/fhir/build/StructureDefinition/no-binding">
        <valueBoolean value="true" />
      </extension>
      <path value="SearchParameter.code" />
      <short value="Code used in URL" />
      <definition value="The code used in the URL or the parameter name in a parameters resource for this search parameter." />
      <comment value="For maximum compatibility, use only lowercase ASCII characters." />
      <min value="1" />
      <max value="1" />
      <type>
        <code value="code" />
      </type>
      <isSummary value="true" />
    </element>
    <element id="SearchParameter.base">
      <path value="SearchParameter.base" />
      <short value="The resource type(s) this search parameter applies to" />
      <definition value="The base resource type(s) that this search parameter can be used against." />
      <comment value="A search parameter must always apply to at least one resource type. When search parameters apply to more than one resource type, they can be used against any of the listed resource types, or in a cross-type search (see [Cross Resource Search](http.html#xres-search))." />
      <min value="1" />
      <max value="*" />
      <type>
        <code value="code" />
      </type>
      <isSummary value="true" />
      <binding>
        <extension url="http://hl7.org/fhir/StructureDefinition/elementdefinition-bindingName">
          <valueString value="ResourceType" />
        </extension>
        <extension url="http://hl7.org/fhir/StructureDefinition/elementdefinition-isCommonBinding">
          <valueBoolean value="true" />
        </extension>
        <strength value="required" />
        <description value="One of the resource types defined as part of this version of FHIR." />
        <valueSet value="http://hl7.org/fhir/ValueSet/resource-types" />
      </binding>
    </element>
    <element id="SearchParameter.type">
      <path value="SearchParameter.type" />
      <short value="number | date | string | token | reference | composite | quantity | uri | special" />
      <definition value="The type of value that a search parameter may contain, and how the content is interpreted." />
      <min value="1" />
      <max value="1" />
      <type>
        <code value="code" />
      </type>
      <isSummary value="true" />
      <binding>
        <extension url="http://hl7.org/fhir/StructureDefinition/elementdefinition-bindingName">
          <valueString value="SearchParamType" />
        </extension>
        <extension url="http://hl7.org/fhir/StructureDefinition/elementdefinition-isCommonBinding">
          <valueBoolean value="true" />
        </extension>
        <strength value="required" />
        <description value="Data types allowed to be used for search parameters." />
        <valueSet value="http://hl7.org/fhir/ValueSet/search-param-type" />
      </binding>
    </element>
    <element id="SearchParameter.expression">
      <path value="SearchParameter.expression" />
      <short value="FHIRPath expression that extracts the values" />
      <definition value="A FHIRPath expression that returns a set of elements for the search parameter." />
      <comment value="Note that the elements returned by the expression are sometimes complex elements where logic is required to determine quite how to handle them; e.g. CodeableConcepts may contain text and/or multiple codings, where the codings themselves contain a code and a system. For composite search parameters, the outcome of the expression must a collection of base elements from which the composites are derived." />
      <min value="0" />
      <max value="1" />
      <type>
        <code value="string" />
      </type>
      <condition value="spd-1" />
    </element>
    <element id="SearchParameter.xpath">
      <path value="SearchParameter.xpath" />
      <short value="XPath that extracts the values" />
      <definition value="An XPath expression that returns a set of elements for the search parameter." />
      <comment value="Note that the elements returned by the XPath are sometimes complex elements where logic is required to determine quite how to handle them; e.g. CodeableConcepts may contain text and/or multiple codings, where the codings themselves contain a code and a system." />
      <min value="0" />
      <max value="1" />
      <type>
        <code value="string" />
      </type>
      <condition value="spd-1" />
    </element>
    <element id="SearchParameter.xpathUsage">
      <path value="SearchParameter.xpathUsage" />
      <short value="normal | phonetic | nearby | distance | other" />
      <definition value="How the search parameter relates to the set of elements returned by evaluating the xpath query." />
      <min value="0" />
      <max value="1" />
      <type>
        <code value="code" />
      </type>
      <condition value="spd-1" />
      <binding>
        <extension url="http://hl7.org/fhir/StructureDefinition/elementdefinition-bindingName">
          <valueString value="XPathUsageType" />
        </extension>
        <strength value="required" />
        <description value="How a search parameter relates to the set of elements returned by evaluating its xpath query." />
        <valueSet value="http://hl7.org/fhir/ValueSet/search-xpath-usage" />
      </binding>
    </element>
    <element id="SearchParameter.target">
      <path value="SearchParameter.target" />
      <short value="Types of resource (if a resource reference)" />
      <definition value="Types of resource (if a resource is referenced)." />
      <min value="0" />
      <max value="*" />
      <type>
        <code value="code" />
      </type>
      <binding>
        <extension url="http://hl7.org/fhir/StructureDefinition/elementdefinition-bindingName">
          <valueString value="ResourceType" />
        </extension>
        <extension url="http://hl7.org/fhir/StructureDefinition/elementdefinition-isCommonBinding">
          <valueBoolean value="true" />
        </extension>
        <strength value="required" />
        <description value="One of the resource types defined as part of this version of FHIR." />
        <valueSet value="http://hl7.org/fhir/ValueSet/resource-types" />
      </binding>
    </element>
    <element id="SearchParameter.multipleOr">
      <path value="SearchParameter.multipleOr" />
      <short value="Allow multiple values per parameter (or)" />
      <definition value="Whether multiple values are allowed for each time the parameter exists. Values are separated by commas, and the parameter matches if any of the values match." />
      <min value="0" />
      <max value="1" />
      <type>
        <code value="boolean" />
      </type>
    </element>
    <element id="SearchParameter.multipleAnd">
      <path value="SearchParameter.multipleAnd" />
      <short value="Allow multiple parameters (and)" />
      <definition value="Whether multiple parameters are allowed - e.g. more than one parameter with the same name. The search matches if all the parameters match." />
      <min value="0" />
      <max value="1" />
      <type>
        <code value="boolean" />
      </type>
    </element>
    <element id="SearchParameter.comparator">
      <path value="SearchParameter.comparator" />
      <short value="eq | ne | gt | lt | ge | le | sa | eb | ap" />
      <definition value="Comparators supported for the search parameter." />
      <comment value="If no comparators are listed, clients should not expect servers to support any comparators." />
      <min value="0" />
      <max value="*" />
      <type>
        <code value="code" />
      </type>
      <binding>
        <extension url="http://hl7.org/fhir/StructureDefinition/elementdefinition-bindingName">
          <valueString value="SearchComparator" />
        </extension>
        <strength value="required" />
        <description value="What Search Comparator Codes are supported in search." />
        <valueSet value="http://hl7.org/fhir/ValueSet/search-comparator" />
      </binding>
    </element>
    <element id="SearchParameter.modifier">
      <path value="SearchParameter.modifier" />
      <short value="missing | exact | contains | not | text | in | not-in | below | above | type | identifier | ofType" />
      <definition value="A modifier supported for the search parameter." />
      <min value="0" />
      <max value="*" />
      <type>
        <code value="code" />
      </type>
      <binding>
        <extension url="http://hl7.org/fhir/StructureDefinition/elementdefinition-bindingName">
          <valueString value="SearchModifierCode" />
        </extension>
        <strength value="required" />
        <description value="A supported modifier for a search parameter." />
        <valueSet value="http://hl7.org/fhir/ValueSet/search-modifier-code" />
      </binding>
    </element>
    <element id="SearchParameter.chain">
      <path value="SearchParameter.chain" />
      <short value="Chained names supported" />
      <definition value="Contains the names of any search parameters which may be chained to the containing search parameter. Chained parameters may be added to search parameters of type reference and specify that resources will only be returned if they contain a reference to a resource which matches the chained parameter value. Values for this field should be drawn from SearchParameter.code for a parameter on the target resource type." />
      <comment value="Systems are not required to list all the chain names they support, but if they don't list them, clients might not know to use them." />
      <min value="0" />
      <max value="*" />
      <type>
        <code value="string" />
      </type>
    </element>
    <element id="SearchParameter.component">
      <path value="SearchParameter.component" />
      <short value="For Composite resources to define the parts" />
      <definition value="Used to define the parts of a composite search parameter." />
      <min value="0" />
      <max value="*" />
      <type>
        <code value="BackboneElement" />
      </type>
    </element>
    <element id="SearchParameter.component.definition">
      <path value="SearchParameter.component.definition" />
      <short value="Defines how the part works" />
      <definition value="The definition of the search parameter that describes this part." />
      <min value="1" />
      <max value="1" />
      <type>
        <code value="canonical" />
        <targetProfile value="http://hl7.org/fhir/StructureDefinition/SearchParameter" />
      </type>
    </element>
    <element id="SearchParameter.component.expression">
      <path value="SearchParameter.component.expression" />
      <short value="Subexpression relative to main expression" />
      <definition value="A sub-expression that defines how to extract values for this component from the output of the main SearchParameter.expression." />
      <comment value="This expression overrides the expression in the definition and extracts the index values from the outcome of the composite expression." />
      <min value="1" />
      <max value="1" />
      <type>
        <code value="string" />
      </type>
    </element>
  </differential>
</StructureDefinition>