Operation Definition

<?xml version="1.0" encoding="UTF-8"?>

<OperationDefinition xmlns="http://hl7.org/fhir">
  <id value="ValueSet-expand"/> 
  <text> 
    <status value="extensions"/> 
    <div xmlns="http://www.w3.org/1999/xhtml">
      <p> URL: [base]/ValueSet/$expand</p> 
      <p> URL: [base]/ValueSet/[id]/$expand</p> 
      <p> Parameters</p> 
      <table class="grid">
        <tr> 
          <td> 
            <b> Use</b> 
          </td> 
          <td> 
            <b> Name</b> 
          </td> 
          <td> 
            <b> Scope</b> 
          </td> 
          <td> 
            <b> Cardinality</b> 
          </td> 
          <td> 
            <b> Type</b> 
          </td> 
          <td> 
            <b> Binding</b> 
          </td> 
          <td> 
            <b> Documentation</b> 
          </td> 
        </tr> 
        <tr> 
          <td> IN</td> 
          <td> url</td> 
          <td> type</td> 
          <td> 0..1</td> 
          <td> 
            <a href="datatypes.html#uri">uri</a> 
          </td> 
          <td/>  
          <td> 
            <div> 
              <p> A canonical reference to a value set. The server must know the value set (e.g.
                 it is defined explicitly in the server's value sets, or it is defined implicitly
                 by some code system known to the server</p> 

            </div> 
          </td> 
        </tr> 
        <tr> 
          <td> IN</td> 
          <td> valueSet</td> 
          <td> type</td> 
          <td> 0..1</td> 
          <td> 
            <a href="valueset.html">ValueSet</a> 
          </td> 
          <td/>  
          <td> 
            <div> 
              <p> The value set is provided directly as part of the request. Servers may choose not
                 to accept value sets in this fashion</p> 

            </div> 
          </td> 
        </tr> 
        <tr> 
          <td> IN</td> 
          <td> valueSetVersion</td> 
          <td> type</td> 
          <td> 0..1</td> 
          <td> 
            <a href="datatypes.html#string">string</a> 
          </td> 
          <td/>  
          <td> 
            <div> 
              <p> The identifier that is used to identify a specific version of the value set to
                 be used when generating the expansion. This is an arbitrary value managed by the
                 value set 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.</p> 

            </div> 
          </td> 
        </tr> 
        <tr> 
          <td> IN</td> 
          <td> context</td> 
          <td/>  
          <td> 0..1</td> 
          <td> 
            <a href="datatypes.html#uri">uri</a> 
          </td> 
          <td/>  
          <td> 
            <div> 
              <p> The context of the value set, so that the server can resolve this to a value set
                 to expand. The recommended format for this URI is [Structure Definition URL]#[name
                 or path into structure definition] e.g. http://hl7.org/fhir/StructureDefinition/observation-h
                spc-height-hspcheight#Observation.interpretation. Other forms may be used but are
                 not defined. This form is only usable if the terminology server also has access
                 to the conformance registry that the server is using, but can be used to delegate
                 the mapping from an application context to a binding at run-time</p> 

            </div> 
          </td> 
        </tr> 
        <tr> 
          <td> IN</td> 
          <td> contextDirection</td> 
          <td/>  
          <td> 0..1</td> 
          <td> 
            <a href="datatypes.html#code">code</a> 
          </td> 
          <td/>  
          <td> 
            <div> 
              <p> If a context is provided, a context direction may also be provided. Valid values
                 are:</p> 

              <ul> 

                <li> 'incoming': the codes a client can use for PUT/POST operations,  and</li> 

                <li> 'outgoing', the codes a client might receive from the server.</li> 

              </ul> 

              <p> The purpose is to inform the server whether to use the value set associated with
                 the context for reading or writing purposes (note: for most elements, this is the
                 same value set, but there are a few elements where the reading and writing value
                 sets are different)</p> 

            </div> 
          </td> 
        </tr> 
        <tr> 
          <td> IN</td> 
          <td> filter</td> 
          <td/>  
          <td> 0..1</td> 
          <td> 
            <a href="datatypes.html#string">string</a> 
          </td> 
          <td/>  
          <td> 
            <div> 
              <p> A text filter that is applied to restrict the codes that are returned (this is
                 useful in a UI context). The interpretation of this is delegated to the server
                 in order to allow to determine the most optimal search approach for the context.
                 The server can document the way this parameter works in 
                <a href="terminologycapabilities.html">TerminologyCapabilities</a> ..expansion.textFilter. Typical usage of this parameter includes functionality
                 like:
              </p> 

              <ul> 

                <li> using left matching e.g. &quot;acut ast&quot;</li> 

                <li> allowing for wild cards such as %, &amp;, ?</li> 

                <li> searching on definition as well as display(s)</li> 

                <li> allowing for search conditions (and / or / exclusions)</li> 

              </ul> 

              <p> Text Search engines such as Lucene or Solr, long with their considerable functionality,
                 might also be used. The optional text search might also be code system specific,
                 and servers might have different implementations for different code systems</p> 

            </div> 
          </td> 
        </tr> 
        <tr> 
          <td> IN</td> 
          <td> date</td> 
          <td/>  
          <td> 0..1</td> 
          <td> 
            <a href="datatypes.html#dateTime">dateTime</a> 
          </td> 
          <td/>  
          <td> 
            <div> 
              <p> The date for which the expansion should be generated.  if a date is provided, it
                 means that the server should use the value set / code system definitions as they
                 were on the given date, or return an error if this is not possible.  Normally,
                 the date is the current conditions (which is the default value) but under some
                 circumstances, systems need to generate an expansion as it would have been in the
                 past. A typical example of this would be where code selection is constrained to
                 the set of codes that were available when the patient was treated, not when the
                 record is being edited. Note that which date is appropriate is a matter for implementation
                 policy.</p> 

            </div> 
          </td> 
        </tr> 
        <tr> 
          <td> IN</td> 
          <td> offset</td> 
          <td/>  
          <td> 0..1</td> 
          <td> 
            <a href="datatypes.html#integer">integer</a> 
          </td> 
          <td/>  
          <td> 
            <div> 
              <p> Paging support - where to start if a subset is desired (default = 0). Offset is
                 number of records (not number of pages)</p> 

            </div> 
          </td> 
        </tr> 
        <tr> 
          <td> IN</td> 
          <td> count</td> 
          <td/>  
          <td> 0..1</td> 
          <td> 
            <a href="datatypes.html#integer">integer</a> 
          </td> 
          <td/>  
          <td> 
            <div> 
              <p> Paging support - how many codes should be provided in a partial page view. Paging
                 only applies to flat expansions - servers ignore paging if the expansion is not
                 flat.  If count = 0, the client is asking how large the expansion is. Servers SHOULD
                 honor this request for hierarchical expansions as well, and simply return the overall
                 count</p> 

            </div> 
          </td> 
        </tr> 
        <tr> 
          <td> IN</td> 
          <td> includeDesignations</td> 
          <td/>  
          <td> 0..1</td> 
          <td> 
            <a href="datatypes.html#boolean">boolean</a> 
          </td> 
          <td/>  
          <td> 
            <div> 
              <p> Controls whether concept designations are to be included or excluded in value set
                 expansions</p> 

            </div> 
          </td> 
        </tr> 
        <tr> 
          <td> IN</td> 
          <td> designation</td> 
          <td/>  
          <td> 0..*</td> 
          <td> 
            <a href="datatypes.html#string">string</a> 
          </td> 
          <td/>  
          <td> 
            <div> 
              <p> A 
                <a href="search.html#token">token</a>  that specifies a system+code that is either a use or a language. Designations
                 that match by language or use are included in the expansion. If no designation
                 is specified, it is at the server discretion which designations to return
              </p> 

            </div> 
          </td> 
        </tr> 
        <tr> 
          <td> IN</td> 
          <td> includeDefinition</td> 
          <td/>  
          <td> 0..1</td> 
          <td> 
            <a href="datatypes.html#boolean">boolean</a> 
          </td> 
          <td/>  
          <td> 
            <div> 
              <p> Controls whether the value set definition is included or excluded in value set
                 expansions</p> 

            </div> 
          </td> 
        </tr> 
        <tr> 
          <td> IN</td> 
          <td> activeOnly</td> 
          <td/>  
          <td> 0..1</td> 
          <td> 
            <a href="datatypes.html#boolean">boolean</a> 
          </td> 
          <td/>  
          <td> 
            <div> 
              <p> Controls whether inactive concepts are included or excluded in value set expansions.
                 Note that if the value set explicitly specifies that inactive codes are included,
                 this parameter can still remove them from a specific expansion, but this parameter
                 cannot include them if the value set excludes them</p> 

            </div> 
          </td> 
        </tr> 
        <tr> 
          <td> IN</td> 
          <td> useSupplement</td> 
          <td/>  
          <td> 0..*</td> 
          <td> 
            <a href="datatypes.html#canonical">canonical</a> 
          </td> 
          <td/>  
          <td> 
            <div> 
              <p> The supplement must be used when performing an expansion. Use of this parameter
                 should result in $expand behaving the same way as if the supplements were included
                 in the value set definition using the 
                <a href="http://hl7.org/fhir/extensions/StructureDefinition-valueset-supplement.html">http://hl7.org/fhir/StructureDefinition/valueset-supplement</a> 
              </p> 

            </div> 
          </td> 
        </tr> 
        <tr> 
          <td> IN</td> 
          <td> excludeNested</td> 
          <td/>  
          <td> 0..1</td> 
          <td> 
            <a href="datatypes.html#boolean">boolean</a> 
          </td> 
          <td/>  
          <td> 
            <div> 
              <p> Controls whether or not the value set expansion may nest codes or not (i.e. ValueSet.expansio
                n.contains.contains). If excludeNested is set to true, the expansion MUST be flat
                 (no nesting). If excludeNested is set to false (default),  however, nesting is
                 possible but not required</p> 

            </div> 
          </td> 
        </tr> 
        <tr> 
          <td> IN</td> 
          <td> excludeNotForUI</td> 
          <td/>  
          <td> 0..1</td> 
          <td> 
            <a href="datatypes.html#boolean">boolean</a> 
          </td> 
          <td/>  
          <td> 
            <div> 
              <p> Controls whether or not the value set expansion might include</p> 

              <ul> 

                <li> codes from the CodeSystem with a notSelectable property set to true as specified
                   in 
                  <a href="codesystem.html#status">status</a>  and in 
                  <a href="codesystem-concept-properties.html">Concept Properties</a> 
                </li> 

                <li> nested contains with no code (see 
                  <a href="valueset-definitions.html#ValueSet.expansion.contains.code">Contains</a> )
                </li> 

                <li> nested contains in the ValueSet with 
                  <a href="valueset-definitions.html#ValueSet.expansion.contains.abstract">abstract = true</a> 
                </li> 

              </ul> 

              <p> One purpose of such concepts is helping a user navigate through the list efficiently.
                 If excludeNotForUI is set to true, the concepts as described above will be excluded
                 from the expansion. If excludeNotForUI is set to false (default), all concepts
                 as described above may be part of the expansion. In the FHIR Specification itself,
                 the value set expansions are generated with excludeNotForUI = false, and the expansions
                 used when generating schema / code etc., or performing validation, are all excludeNotForUI
                 = true.</p> 

            </div> 
          </td> 
        </tr> 
        <tr> 
          <td> IN</td> 
          <td> excludePostCoordinated</td> 
          <td/>  
          <td> 0..1</td> 
          <td> 
            <a href="datatypes.html#boolean">boolean</a> 
          </td> 
          <td/>  
          <td> 
            <div> 
              <p> Controls whether or not the value set expansion includes post coordinated codes</p> 

            </div> 
          </td> 
        </tr> 
        <tr> 
          <td> IN</td> 
          <td> displayLanguage</td> 
          <td/>  
          <td> 0..1</td> 
          <td> 
            <a href="datatypes.html#code">code</a> 
          </td> 
          <td/>  
          <td> 
            <div> 
              <p> Specifies the language to be used for description in the expansions i.e. the language
                 to be used for ValueSet.expansion.contains.display</p> 

            </div> 
          </td> 
        </tr> 
        <tr> 
          <td> IN</td> 
          <td> property</td> 
          <td/>  
          <td> 0..*</td> 
          <td> 
            <a href="datatypes.html#string">string</a> 
          </td> 
          <td/>  
          <td> 
            <div> 
              <p> A request to return a particular property in the expansion. The returned property
                 may include subproperties. May be either a code from the code system definition
                 (convenient) or a the formal URI that refers to the property. Note that property
                 names can clash, so using a URI is recommended. The special value '*' means all
                 properties and their sub-properties known to the server</p> 

            </div> 
          </td> 
        </tr> 
        <tr> 
          <td> IN</td> 
          <td> exclude-system</td> 
          <td/>  
          <td> 0..*</td> 
          <td> 
            <a href="datatypes.html#canonical">canonical</a> 
          </td> 
          <td/>  
          <td> 
            <div> 
              <p> Code system, or a particular version of a code system to be excluded from the value
                 set expansion. The format is the same as a canonical URL: [system]|[version] -
                 e.g. http://loinc.org|2.56</p> 

            </div> 
          </td> 
        </tr> 
        <tr> 
          <td> IN</td> 
          <td> system-version</td> 
          <td/>  
          <td> 0..*</td> 
          <td> 
            <a href="datatypes.html#canonical">canonical</a> 
          </td> 
          <td/>  
          <td> 
            <div> 
              <p> Specifies a version to use for a system, if the value set does not specify which
                 one to use. The format is the same as a canonical URL: [system]|[version] - e.g.
                 http://loinc.org|2.56</p> 

            </div> 
          </td> 
        </tr> 
        <tr> 
          <td> IN</td> 
          <td> check-system-version</td> 
          <td/>  
          <td> 0..*</td> 
          <td> 
            <a href="datatypes.html#canonical">canonical</a> 
          </td> 
          <td/>  
          <td> 
            <div> 
              <p> Edge Case: Specifies a version to use for a system. If a value set specifies a
                 different version, an error is returned instead of the expansion. The format is
                 the same as a canonical URL: [system]|[version] - e.g. http://loinc.org|2.56</p> 

            </div> 
          </td> 
        </tr> 
        <tr> 
          <td> IN</td> 
          <td> force-system-version</td> 
          <td/>  
          <td> 0..*</td> 
          <td> 
            <a href="datatypes.html#canonical">canonical</a> 
          </td> 
          <td/>  
          <td> 
            <div> 
              <p> Edge Case: Specifies a version to use for a system. This parameter overrides any
                 specified version in the value set (and any it depends on). The format is the same
                 as a canonical URL: [system]|[version] - e.g. http://loinc.org|2.56. Note that
                 this has obvious safety issues, in that it may result in a value set expansion
                 giving a different list of codes that is both wrong and unsafe, and implementers
                 should only use this capability reluctantly. It primarily exists to deal with situations
                 where specifications have fallen into decay as time passes. If the value is override,
                 the version used SHALL explicitly be represented in the expansion parameters</p> 

            </div> 
          </td> 
        </tr> 
        <tr> 
          <td> OUT</td> 
          <td> return</td> 
          <td/>  
          <td> 1..1</td> 
          <td> 
            <a href="valueset.html">ValueSet</a> 
          </td> 
          <td/>  
          <td> 
            <div> 
              <p> The result of the expansion. Servers generating expansions SHOULD ensure that all
                 the parameters that affect the contents of the expansion are recorded in the ValueSet.expansi
                on.parameter list</p> 

            </div> 
          </td> 
        </tr> 
      </table> 
      <div> 
        <p> The value set expansion returned by this query should be treated as a transient
           result that will change over time (whether it does or not depends on how the value
           set is specified), so applications should repeat the operation each time the value
           set is used.</p> 

        <p> When available, ValueSet.status and ValueSet.version from the ValueSet resource
           instance which contains the definition SHALL be persisted to the ValueSet resource
           instance which contains the expansion.</p> 

        <p> If the expansion is too large (at the discretion of the server), the server MAY
           return an error (OperationOutcome with code too-costly). Clients can work through
           large flat expansions in a set of pages (partial views of the full expansion) instead
           of just getting the full expansion in a single exchange by using offset and count
           parameters, or use the count parameter to request a subset of the expansion for
           limited purposes. Servers are not obliged to support paging, but if they do, SHALL
           support both the offset and count parameters. Hierarchical expansions are not subject
           to paging and servers simply return the entire expansion.</p> 

        <p> Different servers may return different results from expanding a value set for the
           following reasons:</p> 

        <ul> 

          <li> The underlying code systems are different (e.g. different versions, possibly with
             different defined behavior)</li> 

          <li> The server optimizes filter includes differently, such as sorting by code frequency</li> 

          <li> Servers introduce arbitrary groups to assist a user to navigate the lists based
             either on extensions in the definition, or additional knowledge available to the
             server</li> 

        </ul> 

        <p> When a server cannot correctly expand a value set because it does not fully understand
           the code systems (e.g. it has the wrong version, or incomplete definitions) then
           it SHALL return an error. If the value set itself is unbounded due to the inclusion
           of post-coordinated value sets (e.g. SNOMED CT, UCUM), then the extension 
          <a href="http://hl7.org/fhir/extensions/StructureDefinition-valueset-unclosed.html">http://hl7.org/fhir/StructureDefinition/valueset-unclosed</a>  can be used to indicate that the expansion is incomplete
        </p> 

      </div> 
    </div> 
  </text> 
  <extension url="http://hl7.org/fhir/StructureDefinition/structuredefinition-fmm">
    <valueInteger value="5"/> 
  </extension> 
  <extension url="http://hl7.org/fhir/StructureDefinition/structuredefinition-standards-status">
    <valueCode value="normative"/> 
  </extension> 
  <extension url="http://hl7.org/fhir/StructureDefinition/structuredefinition-wg">
    <valueCode value="vocab"/> 
  </extension> 
  <url value="http://hl7.org/fhir/OperationDefinition/ValueSet-expand"/> 
  <version value="6.0.0-ballot1"/> 
  <name value="Expand"/> 
  <title value="Value Set Expansion"/> 
  <status value="active"/> 
  <kind value="operation"/> 
  <experimental value="false"/> 
  <date value="2023-12-18T15:12:07+11:00"/> 
  <publisher value="HL7 International / Terminology Infrastructure"/> 
  <contact> 
    <telecom> 
      <system value="url"/> 
      <value value="http://hl7.org/fhir"/> 
    </telecom> 
    <telecom> 
      <system value="email"/> 
      <value value="fhir@lists.hl7.org"/> 
    </telecom> 
  </contact> 
  <contact> 
    <telecom> 
      <system value="url"/> 
      <value value="http://www.hl7.org/Special/committees/Vocab"/> 
    </telecom> 
  </contact> 
  <description value="The definition of a value set is used to create a simple collection of codes suitable
   for use for data entry or validation. 

If the operation is not called at the instance level, one of the in parameters
   url, context or valueSet must be provided.  An expanded value set will be returned,
   or an OperationOutcome with an error message."/> 
  <jurisdiction> 
    <coding> 
      <system value="http://unstats.un.org/unsd/methods/m49/m49.htm"/> 
      <code value="001"/> 
      <display value="World"/> 
    </coding> 
  </jurisdiction> 
  <affectsState value="false"/> 
  <code value="expand"/> 
  <comment value="The value set expansion returned by this query should be treated as a transient
   result that will change over time (whether it does or not depends on how the value
   set is specified), so applications should repeat the operation each time the value
   set is used.  

When available, ValueSet.status and ValueSet.version from the ValueSet resource
   instance which contains the definition SHALL be persisted to the ValueSet resource
   instance which contains the expansion.   

If the expansion is too large (at the discretion of the server), the server MAY
   return an error (OperationOutcome with code too-costly). Clients can work through
   large flat expansions in a set of pages (partial views of the full expansion) instead
   of just getting the full expansion in a single exchange by using offset and count
   parameters, or use the count parameter to request a subset of the expansion for
   limited purposes. Servers are not obliged to support paging, but if they do, SHALL
   support both the offset and count parameters. Hierarchical expansions are not subject
   to paging and servers simply return the entire expansion.  

Different servers may return different results from expanding a value set for the
   following reasons:  

* The underlying code systems are different (e.g. different versions, possibly
   with different defined behavior) 
* The server optimizes filter includes differently, such as sorting by code frequency
   
* Servers introduce arbitrary groups to assist a user to navigate the lists based
   either on extensions in the definition, or additional knowledge available to the
   server

When a server cannot correctly expand a value set because it does not fully understand
   the code systems (e.g. it has the wrong version, or incomplete definitions) then
   it SHALL return an error. If the value set itself is unbounded due to the inclusion
   of post-coordinated value sets (e.g. SNOMED CT, UCUM), then the extension [http://hl7.org/fhi
  r/StructureDefinition/valueset-unclosed](http://hl7.org/fhir/extensions/StructureDefinition-va
  lueset-unclosed.html) can be used to indicate that the expansion is incomplete"/> 
  <resource value="ValueSet"/> 
  <system value="false"/> 
  <type value="true"/> 
  <instance value="true"/> 
  <parameter> 
    <name value="url"/> 
    <use value="in"/> 
    <scope value="type"/> 
    <min value="0"/> 
    <max value="1"/> 
    <documentation value="A canonical reference to a value set. The server must know the value set (e.g.
     it is defined explicitly in the server's value sets, or it is defined implicitly
     by some code system known to the server"/> 
    <type value="uri"/> 
  </parameter> 
  <parameter> 
    <name value="valueSet"/> 
    <use value="in"/> 
    <scope value="type"/> 
    <min value="0"/> 
    <max value="1"/> 
    <documentation value="The value set is provided directly as part of the request. Servers may choose not
     to accept value sets in this fashion"/> 
    <type value="ValueSet"/> 
  </parameter> 
  <parameter> 
    <name value="valueSetVersion"/> 
    <use value="in"/> 
    <scope value="type"/> 
    <min value="0"/> 
    <max value="1"/> 
    <documentation value="The identifier that is used to identify a specific version of the value set to
     be used when generating the expansion. This is an arbitrary value managed by the
     value set 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."/> 
    <type value="string"/> 
  </parameter> 
  <parameter> 
    <name value="context"/> 
    <use value="in"/> 
    <min value="0"/> 
    <max value="1"/> 
    <documentation value="The context of the value set, so that the server can resolve this to a value set
     to expand. The recommended format for this URI is [Structure Definition URL]#[name
     or path into structure definition] e.g. http://hl7.org/fhir/StructureDefinition/observation-h
    spc-height-hspcheight#Observation.interpretation. Other forms may be used but are
     not defined. This form is only usable if the terminology server also has access
     to the conformance registry that the server is using, but can be used to delegate
     the mapping from an application context to a binding at run-time"/> 
    <type value="uri"/> 
  </parameter> 
  <parameter> 
    <name value="contextDirection"/> 
    <use value="in"/> 
    <min value="0"/> 
    <max value="1"/> 
    <documentation value="If a context is provided, a context direction may also be provided. Valid values
     are: 

* 'incoming': the codes a client can use for PUT/POST operations,  and 
* 'outgoing', the codes a client might receive from the server.

The purpose is to inform the server whether to use the value set associated with
     the context for reading or writing purposes (note: for most elements, this is the
     same value set, but there are a few elements where the reading and writing value
     sets are different)"/> 
    <type value="code"/> 
  </parameter> 
  <parameter> 
    <name value="filter"/> 
    <use value="in"/> 
    <min value="0"/> 
    <max value="1"/> 
    <documentation value="A text filter that is applied to restrict the codes that are returned (this is
     useful in a UI context). The interpretation of this is delegated to the server
     in order to allow to determine the most optimal search approach for the context.
     The server can document the way this parameter works in [TerminologyCapabilities](terminology
    capabilities.html)..expansion.textFilter. Typical usage of this parameter includes
     functionality like:

* using left matching e.g. &quot;acut ast&quot;
* allowing for wild cards such as %, &amp;, ?
* searching on definition as well as display(s)
* allowing for search conditions (and / or / exclusions)

Text Search engines such as Lucene or Solr, long with their considerable functionality,
     might also be used. The optional text search might also be code system specific,
     and servers might have different implementations for different code systems"/> 
    <type value="string"/> 
  </parameter> 
  <parameter> 
    <name value="date"/> 
    <use value="in"/> 
    <min value="0"/> 
    <max value="1"/> 
    <documentation value="The date for which the expansion should be generated.  if a date is provided, it
     means that the server should use the value set / code system definitions as they
     were on the given date, or return an error if this is not possible.  Normally,
     the date is the current conditions (which is the default value) but under some
     circumstances, systems need to generate an expansion as it would have been in the
     past. A typical example of this would be where code selection is constrained to
     the set of codes that were available when the patient was treated, not when the
     record is being edited. Note that which date is appropriate is a matter for implementation
     policy."/> 
    <type value="dateTime"/> 
  </parameter> 
  <parameter> 
    <name value="offset"/> 
    <use value="in"/> 
    <min value="0"/> 
    <max value="1"/> 
    <documentation value="Paging support - where to start if a subset is desired (default = 0). Offset is
     number of records (not number of pages)"/> 
    <type value="integer"/> 
  </parameter> 
  <parameter> 
    <name value="count"/> 
    <use value="in"/> 
    <min value="0"/> 
    <max value="1"/> 
    <documentation value="Paging support - how many codes should be provided in a partial page view. Paging
     only applies to flat expansions - servers ignore paging if the expansion is not
     flat.  If count = 0, the client is asking how large the expansion is. Servers SHOULD
     honor this request for hierarchical expansions as well, and simply return the overall
     count"/> 
    <type value="integer"/> 
  </parameter> 
  <parameter> 
    <name value="includeDesignations"/> 
    <use value="in"/> 
    <min value="0"/> 
    <max value="1"/> 
    <documentation value="Controls whether concept designations are to be included or excluded in value set
     expansions"/> 
    <type value="boolean"/> 
  </parameter> 
  <parameter> 
    <name value="designation"/> 
    <use value="in"/> 
    <min value="0"/> 
    <max value="*"/> 
    <documentation value="A [token](search.html#token) that specifies a system+code that is either a use
     or a language. Designations that match by language or use are included in the expansion.
     If no designation is specified, it is at the server discretion which designations
     to return"/> 
    <type value="string"/> 
  </parameter> 
  <parameter> 
    <name value="includeDefinition"/> 
    <use value="in"/> 
    <min value="0"/> 
    <max value="1"/> 
    <documentation value="Controls whether the value set definition is included or excluded in value set
     expansions"/> 
    <type value="boolean"/> 
  </parameter> 
  <parameter> 
    <name value="activeOnly"/> 
    <use value="in"/> 
    <min value="0"/> 
    <max value="1"/> 
    <documentation value="Controls whether inactive concepts are included or excluded in value set expansions.
     Note that if the value set explicitly specifies that inactive codes are included,
     this parameter can still remove them from a specific expansion, but this parameter
     cannot include them if the value set excludes them"/> 
    <type value="boolean"/> 
  </parameter> 
  <parameter> 
    <name value="useSupplement"/> 
    <use value="in"/> 
    <min value="0"/> 
    <max value="*"/> 
    <documentation value="The supplement must be used when performing an expansion. Use of this parameter
     should result in $expand behaving the same way as if the supplements were included
     in the value set definition using the [http://hl7.org/fhir/StructureDefinition/valueset-suppl
    ement](http://hl7.org/fhir/extensions/StructureDefinition-valueset-supplement.html)"/> 
    <type value="canonical"/> 
  </parameter> 
  <parameter> 
    <name value="excludeNested"/> 
    <use value="in"/> 
    <min value="0"/> 
    <max value="1"/> 
    <documentation value="Controls whether or not the value set expansion may nest codes or not (i.e. ValueSet.expansio
    n.contains.contains). If excludeNested is set to true, the expansion MUST be flat
     (no nesting). If excludeNested is set to false (default),  however, nesting is
     possible but not required"/> 
    <type value="boolean"/> 
  </parameter> 
  <parameter> 
    <name value="excludeNotForUI"/> 
    <use value="in"/> 
    <min value="0"/> 
    <max value="1"/> 
    <documentation value="Controls whether or not the value set expansion might include

* codes from the CodeSystem with a notSelectable property set to true as specified
     in [status](codesystem.html#status) and in [Concept Properties](codesystem-concept-properties
    .html)
* nested contains with no code (see [Contains](valueset-definitions.html#ValueSet.expansion.c
    ontains.code))
* nested contains in the ValueSet with [abstract = true](valueset-definitions.html#ValueSet.e
    xpansion.contains.abstract)

One purpose of such concepts is helping a user navigate through the list efficiently.
     If excludeNotForUI is set to true, the concepts as described above will be excluded
     from the expansion. If excludeNotForUI is set to false (default), all concepts
     as described above may be part of the expansion. In the FHIR Specification itself,
     the value set expansions are generated with excludeNotForUI = false, and the expansions
     used when generating schema / code etc., or performing validation, are all excludeNotForUI
     = true."/> 
    <type value="boolean"/> 
  </parameter> 
  <parameter> 
    <name value="excludePostCoordinated"/> 
    <use value="in"/> 
    <min value="0"/> 
    <max value="1"/> 
    <documentation value="Controls whether or not the value set expansion includes post coordinated codes"/> 
    <type value="boolean"/> 
  </parameter> 
  <parameter> 
    <name value="displayLanguage"/> 
    <use value="in"/> 
    <min value="0"/> 
    <max value="1"/> 
    <documentation value="Specifies the language to be used for description in the expansions i.e. the language
     to be used for ValueSet.expansion.contains.display"/> 
    <type value="code"/> 
  </parameter> 
  <parameter> 
    <name value="property"/> 
    <use value="in"/> 
    <min value="0"/> 
    <max value="*"/> 
    <documentation value="A request to return a particular property in the expansion. The returned property
     may include subproperties. May be either a code from the code system definition
     (convenient) or a the formal URI that refers to the property. Note that property
     names can clash, so using a URI is recommended. The special value '*' means all
     properties and their sub-properties known to the server"/> 
    <type value="string"/> 
  </parameter> 
  <parameter> 
    <name value="exclude-system"/> 
    <use value="in"/> 
    <min value="0"/> 
    <max value="*"/> 
    <documentation value="Code system, or a particular version of a code system to be excluded from the value
     set expansion. The format is the same as a canonical URL: [system]|[version] -
     e.g. http://loinc.org|2.56"/> 
    <type value="canonical"/> 
  </parameter> 
  <parameter> 
    <name value="system-version"/> 
    <use value="in"/> 
    <min value="0"/> 
    <max value="*"/> 
    <documentation value="Specifies a version to use for a system, if the value set does not specify which
     one to use. The format is the same as a canonical URL: [system]|[version] - e.g.
     http://loinc.org|2.56"/> 
    <type value="canonical"/> 
  </parameter> 
  <parameter> 
    <name value="check-system-version"/> 
    <use value="in"/> 
    <min value="0"/> 
    <max value="*"/> 
    <documentation value="Edge Case: Specifies a version to use for a system. If a value set specifies a
     different version, an error is returned instead of the expansion. The format is
     the same as a canonical URL: [system]|[version] - e.g. http://loinc.org|2.56"/> 
    <type value="canonical"/> 
  </parameter> 
  <parameter> 
    <name value="force-system-version"/> 
    <use value="in"/> 
    <min value="0"/> 
    <max value="*"/> 
    <documentation value="Edge Case: Specifies a version to use for a system. This parameter overrides any
     specified version in the value set (and any it depends on). The format is the same
     as a canonical URL: [system]|[version] - e.g. http://loinc.org|2.56. Note that
     this has obvious safety issues, in that it may result in a value set expansion
     giving a different list of codes that is both wrong and unsafe, and implementers
     should only use this capability reluctantly. It primarily exists to deal with situations
     where specifications have fallen into decay as time passes. If the value is override,
     the version used SHALL explicitly be represented in the expansion parameters"/> 
    <type value="canonical"/> 
  </parameter> 
  <parameter> 
    <name value="return"/> 
    <use value="out"/> 
    <min value="1"/> 
    <max value="1"/> 
    <documentation value="The result of the expansion. Servers generating expansions SHOULD ensure that all
     the parameters that affect the contents of the expansion are recorded in the ValueSet.expansi
    on.parameter list"/> 
    <type value="ValueSet"/> 
  </parameter> 
</OperationDefinition>