Quality Measure Implementation Guide
2.0.0-ballot - STU 2 Ballot

Quality Measure Implementation Guide - Downloaded Version null See the Directory of published versions

## Extension: CQM Population Basis - XML Profile

Page standards status: Trial-use | Maturity Level: 4

XML representation of the cqm-populationBasis extension.

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    <StructureDefinition xmlns="http://hl7.org/fhir">
      <id value="cqm-populationBasis"/>
      <language value="en"/>
      <text>
        <status value="extensions"/>
        <div xmlns="http://www.w3.org/1999/xhtml"><p class="res-header-id"><b>Generated Narrative: StructureDefinition cqm-populationBasis</b></p><a name="cqm-populationBasis"> </a><a name="hccqm-populationBasis"> </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 : var(--ig-left,left); background-color: white; border: 0px #F0F0F0 solid; padding:0px 4px 0px 4px; padding-top: 3px; padding-bottom: 3px" 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 : var(--ig-left,left); background-color: white; border: 0px #F0F0F0 solid; padding:0px 4px 0px 4px; padding-top: 3px; padding-bottom: 3px" 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 : var(--ig-left,left); background-color: white; border: 0px #F0F0F0 solid; padding:0px 4px 0px 4px; padding-top: 3px; padding-bottom: 3px" 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="vertical-align: top; text-align : var(--ig-left,left); background-color: white; border: 0px #F0F0F0 solid; padding:0px 4px 0px 4px; padding-top: 3px; padding-bottom: 3px; 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 : var(--ig-left,left); background-color: white; border: 0px #F0F0F0 solid; padding:0px 4px 0px 4px; padding-top: 3px; padding-bottom: 3px" 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, " 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 : var(--ig-left,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-cqm-populationBasis-definitions.html#Extension" title="The population basis specifies the type of elements in the population. For a subject-based measure, this is boolean (because the subject and the population basis are the same, and the population criteria define yes/no values for each individual in the population). For measures that have a population basis that is different than the subject, this element specifies the type of the population basis. For example, an encounter-based measure has a subject of Patient and a population basis of Encounter, and the population criteria all return lists of Encounters.">Extension</a><a name="Extension"> </a></td><td style="vertical-align: top; text-align : var(--ig-left,left); background-color: white; border: 0px #F0F0F0 solid; padding:0px 4px 0px 4px" class="hierarchy"><a style="padding-left: 3px; padding-right: 3px; border: 1px maroon solid; font-weight: bold; color: #301212; background-color: #fdf4f4;; padding-left: 3px; padding-right: 3px; border: 1px maroon solid; font-weight: bold; color: #301212; background-color: #fdf4f4;" href="http://hl7.org/fhir/R4/conformance-rules.html#constraints" title="This element has or is affected by constraints ( popBasis-1 )">C</a></td><td style="vertical-align: top; text-align : var(--ig-left,left); background-color: white; border: 0px #F0F0F0 solid; padding:0px 4px 0px 4px" class="hierarchy">0..*</td><td style="vertical-align: top; text-align : var(--ig-left,left); background-color: white; border: 0px #F0F0F0 solid; padding:0px 4px 0px 4px" class="hierarchy"><a href="http://hl7.org/fhir/R4/extensibility.html#Extension">Extension</a></td><td style="vertical-align: top; text-align : var(--ig-left,left); background-color: white; border: 0px #F0F0F0 solid; padding:0px 4px 0px 4px" class="hierarchy">What type of population<br class="constraint"/><span title="null" class="constraint">Constraints: </span><span style="font-weight:bold" title="If DataRequirement.type is present, it may only contain the elements 'profile' and 'codeFilter'." class="constraint">popBasis-1</span><br/></td></tr>
    <tr style="border: 0px #F0F0F0 solid; padding:0px; vertical-align: top; background-color: #F7F7F7"><td style="vertical-align: top; text-align : var(--ig-left,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_primitive.png" alt="." style="background-color: #F7F7F7; background-color: inherit" title="Primitive Data Type" class="hierarchy"/> <a href="StructureDefinition-cqm-populationBasis-definitions.html#Extension.url">url</a><a name="Extension.url"> </a></td><td style="vertical-align: top; text-align : var(--ig-left,left); background-color: #F7F7F7; border: 0px #F0F0F0 solid; padding:0px 4px 0px 4px" class="hierarchy"/><td style="vertical-align: top; text-align : var(--ig-left,left); background-color: #F7F7F7; 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 : var(--ig-left,left); background-color: #F7F7F7; border: 0px #F0F0F0 solid; padding:0px 4px 0px 4px" class="hierarchy"><a href="http://hl7.org/fhir/R4/datatypes.html#uri">uri</a></td><td style="vertical-align: top; text-align : var(--ig-left,left); background-color: #F7F7F7; border: 0px #F0F0F0 solid; padding:0px 4px 0px 4px" class="hierarchy"><span style="color: darkgreen">&quot;http://hl7.org/fhir/uv/cqm/StructureDefinition/cqm-populationBasis&quot;</span></td></tr>
    <tr style="border: 0px #F0F0F0 solid; padding:0px; vertical-align: top; background-color: white"><td style="vertical-align: top; text-align : var(--ig-left,left); background-color: white; border: 0px #F0F0F0 solid; padding:0px 4px 0px 4px; white-space: nowrap; background-image: url(tbl_bck01.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_choice.gif" alt="." style="background-color: white; background-color: inherit" title="Choice of Types" class="hierarchy"/> <a href="StructureDefinition-cqm-populationBasis-definitions.html#Extension.value[x]">value[x]</a><a name="Extension.value_x_"> </a></td><td style="vertical-align: top; text-align : var(--ig-left,left); background-color: white; border: 0px #F0F0F0 solid; padding:0px 4px 0px 4px" class="hierarchy"/><td style="vertical-align: top; text-align : var(--ig-left,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">1</span></td><td style="vertical-align: top; text-align : var(--ig-left,left); background-color: white; border: 0px #F0F0F0 solid; padding:0px 4px 0px 4px" class="hierarchy"/><td style="vertical-align: top; text-align : var(--ig-left,left); background-color: white; border: 0px #F0F0F0 solid; padding:0px 4px 0px 4px" class="hierarchy"><span style="opacity: 0.5">Value of extension</span><br class="binding"/><span style="font-weight:bold" title="null" class="binding">Binding: </span><a href="http://hl7.org/fhir/R4/valueset-all-types.html" title="http://hl7.org/fhir/ValueSet/all-types" class="binding">FHIRAllTypes</a><span title="null" class="binding"> (</span><a href="http://hl7.org/fhir/R4/terminologies.html#required" title="To be conformant, the concept in this element SHALL be from the specified value set." class="binding">required</a><span title="null" class="binding">)</span><span title="null" class="binding">: </span><span title="null" class="binding">The type of elements in the population</span></td></tr>
    <tr style="border: 0px #F0F0F0 solid; padding:0px; vertical-align: top; background-color: #F7F7F7"><td style="vertical-align: top; text-align : var(--ig-left,left); background-color: #F7F7F7; border: 0px #F0F0F0 solid; padding:0px 4px 0px 4px; white-space: nowrap; background-image: url(tbl_bck010.png)" class="hierarchy"><img src="tbl_spacer.png" alt="." style="background-color: inherit" class="hierarchy"/><img src="tbl_blank.png" alt="." style="background-color: inherit" class="hierarchy"/><img src="tbl_vjoin.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"/> <span title="Base StructureDefinition for code type: A string which has at least one character and no leading or trailing whitespace and where there is no whitespace other than single spaces in the contents">valueCode</span></td><td style="vertical-align: top; text-align : var(--ig-left,left); background-color: #F7F7F7; border: 0px #F0F0F0 solid; padding:0px 4px 0px 4px" class="hierarchy"/><td style="vertical-align: top; text-align : var(--ig-left,left); background-color: #F7F7F7; border: 0px #F0F0F0 solid; padding:0px 4px 0px 4px" class="hierarchy"/><td style="vertical-align: top; text-align : var(--ig-left,left); background-color: #F7F7F7; border: 0px #F0F0F0 solid; padding:0px 4px 0px 4px" class="hierarchy"><a href="http://hl7.org/fhir/R4/datatypes.html#code">code</a></td><td style="vertical-align: top; text-align : var(--ig-left,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 : var(--ig-left,left); background-color: white; border: 0px #F0F0F0 solid; padding:0px 4px 0px 4px; white-space: nowrap; background-image: url(tbl_bck000.png)" class="hierarchy"><img src="tbl_spacer.png" alt="." style="background-color: inherit" class="hierarchy"/><img src="tbl_blank.png" alt="." style="background-color: inherit" class="hierarchy"/><img src="tbl_vjoin_end.png" alt="." style="background-color: inherit" class="hierarchy"/><img src="icon_datatype.gif" alt="." style="background-color: white; background-color: inherit" title="Data Type" class="hierarchy"/> <span title="Base StructureDefinition for DataRequirement Type: Describes a required data item for evaluation in terms of the type of data, and optional code or date-based filters of the data.">valueDataRequirement</span></td><td style="vertical-align: top; text-align : var(--ig-left,left); background-color: white; border: 0px #F0F0F0 solid; padding:0px 4px 0px 4px" class="hierarchy"/><td style="vertical-align: top; text-align : var(--ig-left,left); background-color: white; border: 0px #F0F0F0 solid; padding:0px 4px 0px 4px" class="hierarchy"/><td style="vertical-align: top; text-align : var(--ig-left,left); background-color: white; border: 0px #F0F0F0 solid; padding:0px 4px 0px 4px" class="hierarchy"><a href="http://hl7.org/fhir/R4/metadatatypes.html#DataRequirement">DataRequirement</a></td><td style="vertical-align: top; text-align : var(--ig-left,left); background-color: white; border: 0px #F0F0F0 solid; padding:0px 4px 0px 4px" class="hierarchy"/></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, " 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="cqi"/>
      </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/cqm/ImplementationGuide/hl7.fhir.uv.cqm"/>
          </extension>
        </valueInteger>
      </extension>
      <extension
                 url="http://hl7.org/fhir/StructureDefinition/structuredefinition-standards-status">
        <valueCode value="trial-use">
          <extension
                     url="http://hl7.org/fhir/StructureDefinition/structuredefinition-conformance-derivedFrom">
            <valueCanonical
                            value="http://hl7.org/fhir/uv/cqm/ImplementationGuide/hl7.fhir.uv.cqm"/>
          </extension>
        </valueCode>
      </extension>
      <url
           value="http://hl7.org/fhir/uv/cqm/StructureDefinition/cqm-populationBasis"/>
      <identifier>
        <system value="urn:ietf:rfc:3986"/>
        <value value="urn:oid:2.16.840.1.113883.4.642.40.61.42.21"/>
      </identifier>
      <version value="1.0.0"/>
      <name value="CQMPopulationBasis"/>
      <title value="CQM Population Basis"/>
      <status value="active"/>
      <experimental value="false"/>
      <date value="2026-04-07T02:06:45+10:00"/>
      <publisher value="HL7 International / Clinical Quality Information"/>
      <contact>
        <telecom>
          <system value="url"/>
          <value value="http://www.hl7.org/Special/committees/cqi"/>
        </telecom>
      </contact>
      <description
                   value="The population basis specifies the type of elements in the population. For a subject-based measure, this is boolean (because the subject and the population basis are the same, and the population criteria define yes/no values for each individual in the population). For measures that have a population basis that is different than the subject, this element specifies the type of the population basis. For example, an encounter-based measure has a subject of Patient and a population basis of Encounter, and the population criteria all return lists of Encounters. Note that the subject of a measure can be found in the element [subject[x].](https://hl7.org/fhir/uv/cqm/StructureDefinition-cqm-computablemeasure-definitions.html#Measure.subject[x])"/>
      <jurisdiction>
        <coding>
          <system value="http://unstats.un.org/unsd/methods/m49/m49.htm"/>
          <code value="001"/>
        </coding>
      </jurisdiction>
      <purpose
               value="A measure specification needs to be able to specify the expected result type of each population criteria. This value SHALL be consistent with the result type of all population-level criteria in the measure."/>
      <fhirVersion value="4.0.1"/>
      <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="Measure"/>
      </context>
      <context>
        <type value="element"/>
        <expression value="Measure.group"/>
      </context>
      <context>
        <type value="element"/>
        <expression value="Measure.group.population"/>
      </context>
      <type value="Extension"/>
      <baseDefinition value="http://hl7.org/fhir/StructureDefinition/Extension"/>
      <derivation value="constraint"/>
      <snapshot>
        <extension
                   url="http://hl7.org/fhir/tools/StructureDefinition/snapshot-base-version">
          <valueString value="4.0.1"/>
        </extension>
        <element id="Extension">
          <path value="Extension"/>
          <short value="What type of population"/>
          <definition
                      value="The population basis specifies the type of elements in the population. For a subject-based measure, this is boolean (because the subject and the population basis are the same, and the population criteria define yes/no values for each individual in the population). For measures that have a population basis that is different than the subject, this element specifies the type of the population basis. For example, an encounter-based measure has a subject of Patient and a population basis of Encounter, and the population criteria all return lists of Encounters."/>
          <comment
                   value="In Health Quality Measure Format, this was referred to as the Item Count metadata attribute. If the populationBasis is specified as a data requirement, the type SHALL be present, profile and codeFilter MAY be present, and no other elements are allowed. This usage allows population basis to be stated with more specificity, e.g. CT Scans, rather than just DiagnosticReport."/>
          <min value="0"/>
          <max value="*"/>
          <base>
            <path value="Extension"/>
            <min value="0"/>
            <max value="*"/>
          </base>
          <condition value="ele-1"/>
          <constraint>
            <key value="ele-1"/>
            <severity value="error"/>
            <human value="All FHIR elements must have a @value or children"/>
            <expression
                        value="hasValue() or (children().count() &gt; id.count())"/>
            <xpath value="@value|f:*|h:div"/>
            <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()"/>
            <xpath
                   value="exists(f:extension)!=exists(f:*[starts-with(local-name(.), 'value')])"/>
            <source value="http://hl7.org/fhir/StructureDefinition/Extension"/>
          </constraint>
          <constraint>
            <key value="popBasis-1"/>
            <severity value="error"/>
            <human
                   value="If DataRequirement.type is present, it may only contain the elements 'profile' and 'codeFilter'."/>
            <expression
                        value="value.exists() and value.is(DataRequirement) implies (  value.as(DataRequirement).type.exists() and  value.as(DataRequirement).limit.empty() and  value.as(DataRequirement).sort.empty() and  value.as(DataRequirement).dateFilter.empty() and  value.as(DataRequirement).subject.empty() and  value.as(DataRequirement).mustSupport.empty())"/>
          </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="string"/>
            </extension>
            <code value="http://hl7.org/fhirpath/System.String"/>
          </type>
          <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="Additional content defined by implementations"/>
          <definition
                      value="May be used to represent additional information that is not part of the basic definition of the element. To make the use of extensions safe and manageable, there is a strict set of governance  applied to the definition and use of extensions. Though any implementer can define an extension, there is a set of requirements that SHALL be met as part of the definition of the extension."/>
          <comment
                   value="There can be no stigma associated with the use of extensions by any application, project, or standard - regardless of the institution or jurisdiction that uses or defines the extensions.  The use of extensions is what allows the FHIR specification to retain a core level of simplicity for everyone."/>
          <alias value="extensions"/>
          <alias value="user content"/>
          <min value="0"/>
          <max value="*"/>
          <base>
            <path value="Element.extension"/>
            <min value="0"/>
            <max value="*"/>
          </base>
          <type>
            <code value="Extension"/>
          </type>
          <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())"/>
            <xpath value="@value|f:*|h:div"/>
            <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()"/>
            <xpath
                   value="exists(f:extension)!=exists(f:*[starts-with(local-name(.), &quot;value&quot;)])"/>
            <source value="http://hl7.org/fhir/StructureDefinition/Extension"/>
          </constraint>
          <isModifier value="false"/>
          <isSummary value="false"/>
          <mapping>
            <identity value="rim"/>
            <map value="n/a"/>
          </mapping>
        </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>
            <code value="uri"/>
          </type>
          <fixedUri
                    value="http://hl7.org/fhir/uv/cqm/StructureDefinition/cqm-populationBasis"/>
          <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/R4/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="code"/>
          </type>
          <type>
            <code value="DataRequirement"/>
          </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())"/>
            <xpath value="@value|f:*|h:div"/>
            <source value="http://hl7.org/fhir/StructureDefinition/Element"/>
          </constraint>
          <isModifier value="false"/>
          <isSummary value="false"/>
          <binding>
            <strength value="required"/>
            <description value="The type of elements in the population"/>
            <valueSet value="http://hl7.org/fhir/ValueSet/all-types"/>
          </binding>
          <mapping>
            <identity value="rim"/>
            <map value="N/A"/>
          </mapping>
        </element>
      </snapshot>
      <differential>
        <element id="Extension">
          <path value="Extension"/>
          <short value="What type of population"/>
          <definition
                      value="The population basis specifies the type of elements in the population. For a subject-based measure, this is boolean (because the subject and the population basis are the same, and the population criteria define yes/no values for each individual in the population). For measures that have a population basis that is different than the subject, this element specifies the type of the population basis. For example, an encounter-based measure has a subject of Patient and a population basis of Encounter, and the population criteria all return lists of Encounters."/>
          <comment
                   value="In Health Quality Measure Format, this was referred to as the Item Count metadata attribute. If the populationBasis is specified as a data requirement, the type SHALL be present, profile and codeFilter MAY be present, and no other elements are allowed. This usage allows population basis to be stated with more specificity, e.g. CT Scans, rather than just DiagnosticReport."/>
          <min value="0"/>
          <max value="*"/>
          <constraint>
            <key value="popBasis-1"/>
            <severity value="error"/>
            <human
                   value="If DataRequirement.type is present, it may only contain the elements 'profile' and 'codeFilter'."/>
            <expression
                        value="value.exists() and value.is(DataRequirement) implies (  value.as(DataRequirement).type.exists() and  value.as(DataRequirement).limit.empty() and  value.as(DataRequirement).sort.empty() and  value.as(DataRequirement).dateFilter.empty() and  value.as(DataRequirement).subject.empty() and  value.as(DataRequirement).mustSupport.empty())"/>
          </constraint>
        </element>
        <element id="Extension.url">
          <path value="Extension.url"/>
          <type>
            <code value="uri"/>
          </type>
          <fixedUri
                    value="http://hl7.org/fhir/uv/cqm/StructureDefinition/cqm-populationBasis"/>
        </element>
        <element id="Extension.value[x]">
          <path value="Extension.value[x]"/>
          <type>
            <code value="code"/>
          </type>
          <type>
            <code value="DataRequirement"/>
          </type>
          <binding>
            <strength value="required"/>
            <description value="The type of elements in the population"/>
            <valueSet value="http://hl7.org/fhir/ValueSet/all-types"/>
          </binding>
        </element>
      </differential>
    </StructureDefinition>