Quality Measure Implementation Guide
1.0.0 - STU 1

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

## Extension: CQMPopulationBasis - JSON Profile

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

JSON representation of the cqm-populationBasis extension.

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    {
      "resourceType" : "StructureDefinition",
      "id" : "cqm-populationBasis",
      "text" : {
        "status" : "extensions",
        "div" : "<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>\r\n<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>\r\n<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>\r\n<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>\r\n<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>\r\n<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>"
      },
      "extension" : [
        {
          "url" : "http://hl7.org/fhir/StructureDefinition/structuredefinition-wg",
          "valueCode" : "cqi"
        },
        {
          "url" : "http://hl7.org/fhir/StructureDefinition/structuredefinition-fmm",
          "valueInteger" : 4,
          "_valueInteger" : {
            "extension" : [
              {
                "url" : "http://hl7.org/fhir/StructureDefinition/structuredefinition-conformance-derivedFrom",
                "valueCanonical" : "http://hl7.org/fhir/uv/cqm/ImplementationGuide/hl7.fhir.uv.cqm"
              }
            ]
          }
        },
        {
          "url" : "http://hl7.org/fhir/StructureDefinition/structuredefinition-standards-status",
          "valueCode" : "trial-use",
          "_valueCode" : {
            "extension" : [
              {
                "url" : "http://hl7.org/fhir/StructureDefinition/structuredefinition-conformance-derivedFrom",
                "valueCanonical" : "http://hl7.org/fhir/uv/cqm/ImplementationGuide/hl7.fhir.uv.cqm"
              }
            ]
          }
        }
      ],
      "url" : "http://hl7.org/fhir/uv/cqm/StructureDefinition/cqm-populationBasis",
      "identifier" : [
        {
          "system" : "urn:ietf:rfc:3986",
          "value" : "urn:oid:2.16.840.1.113883.4.642.40.61.42.21"
        }
      ],
      "version" : "1.0.0",
      "name" : "CQMPopulationBasis",
      "title" : "CQM Population Basis",
      "status" : "active",
      "experimental" : false,
      "date" : "2025-09-11T18:58:45+00:00",
      "publisher" : "HL7 International / Clinical Quality Information",
      "contact" : [
        {
          "telecom" : [
            {
              "system" : "url",
              "value" : "http://www.hl7.org/Special/committees/cqi"
            }
          ]
        }
      ],
      "description" : "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" : "http://unstats.un.org/unsd/methods/m49/m49.htm",
              "code" : "001"
            }
          ]
        }
      ],
      "purpose" : "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" : "4.0.1",
      "mapping" : [
        {
          "identity" : "rim",
          "uri" : "http://hl7.org/v3",
          "name" : "RIM Mapping"
        }
      ],
      "kind" : "complex-type",
      "abstract" : false,
      "context" : [
        {
          "type" : "element",
          "expression" : "Measure"
        },
        {
          "type" : "element",
          "expression" : "Measure.group"
        },
        {
          "type" : "element",
          "expression" : "Measure.group.population"
        }
      ],
      "type" : "Extension",
      "baseDefinition" : "http://hl7.org/fhir/StructureDefinition/Extension",
      "derivation" : "constraint",
      "snapshot" : {
        "extension" : [
          {
            "url" : "http://hl7.org/fhir/tools/StructureDefinition/snapshot-base-version",
            "valueString" : "4.0.1"
          }
        ],
        "element" : [
          {
            "id" : "Extension",
            "path" : "Extension",
            "short" : "What type of population",
            "definition" : "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" : "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" : 0,
            "max" : "*",
            "base" : {
              "path" : "Extension",
              "min" : 0,
              "max" : "*"
            },
            "condition" : [
              "ele-1"
            ],
            "constraint" : [
              {
                "key" : "ele-1",
                "severity" : "error",
                "human" : "All FHIR elements must have a @value or children",
                "expression" : "hasValue() or (children().count() > id.count())",
                "xpath" : "@value|f:*|h:div",
                "source" : "http://hl7.org/fhir/StructureDefinition/Element"
              },
              {
                "key" : "ext-1",
                "severity" : "error",
                "human" : "Must have either extensions or value[x], not both",
                "expression" : "extension.exists() != value.exists()",
                "xpath" : "exists(f:extension)!=exists(f:*[starts-with(local-name(.), 'value')])",
                "source" : "http://hl7.org/fhir/StructureDefinition/Extension"
              },
              {
                "key" : "popBasis-1",
                "severity" : "error",
                "human" : "If DataRequirement.type is present, it may only contain the elements 'profile' and 'codeFilter'.",
                "expression" : "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())"
              }
            ],
            "isModifier" : false
          },
          {
            "id" : "Extension.id",
            "path" : "Extension.id",
            "representation" : [
              "xmlAttr"
            ],
            "short" : "Unique id for inter-element referencing",
            "definition" : "Unique id for the element within a resource (for internal references). This may be any string value that does not contain spaces.",
            "min" : 0,
            "max" : "1",
            "base" : {
              "path" : "Element.id",
              "min" : 0,
              "max" : "1"
            },
            "type" : [
              {
                "extension" : [
                  {
                    "url" : "http://hl7.org/fhir/StructureDefinition/structuredefinition-fhir-type",
                    "valueUrl" : "string"
                  }
                ],
                "code" : "http://hl7.org/fhirpath/System.String"
              }
            ],
            "isModifier" : false,
            "isSummary" : false,
            "mapping" : [
              {
                "identity" : "rim",
                "map" : "n/a"
              }
            ]
          },
          {
            "id" : "Extension.extension",
            "path" : "Extension.extension",
            "slicing" : {
              "discriminator" : [
                {
                  "type" : "value",
                  "path" : "url"
                }
              ],
              "description" : "Extensions are always sliced by (at least) url",
              "rules" : "open"
            },
            "short" : "Additional content defined by implementations",
            "definition" : "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" : "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" : [
              "extensions",
              "user content"
            ],
            "min" : 0,
            "max" : "*",
            "base" : {
              "path" : "Element.extension",
              "min" : 0,
              "max" : "*"
            },
            "type" : [
              {
                "code" : "Extension"
              }
            ],
            "constraint" : [
              {
                "key" : "ele-1",
                "severity" : "error",
                "human" : "All FHIR elements must have a @value or children",
                "expression" : "hasValue() or (children().count() > id.count())",
                "xpath" : "@value|f:*|h:div",
                "source" : "http://hl7.org/fhir/StructureDefinition/Element"
              },
              {
                "key" : "ext-1",
                "severity" : "error",
                "human" : "Must have either extensions or value[x], not both",
                "expression" : "extension.exists() != value.exists()",
                "xpath" : "exists(f:extension)!=exists(f:*[starts-with(local-name(.), \"value\")])",
                "source" : "http://hl7.org/fhir/StructureDefinition/Extension"
              }
            ],
            "isModifier" : false,
            "isSummary" : false,
            "mapping" : [
              {
                "identity" : "rim",
                "map" : "n/a"
              }
            ]
          },
          {
            "id" : "Extension.url",
            "path" : "Extension.url",
            "representation" : [
              "xmlAttr"
            ],
            "short" : "identifies the meaning of the extension",
            "definition" : "Source of the definition for the extension code - a logical name or a URL.",
            "comment" : "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" : 1,
            "max" : "1",
            "base" : {
              "path" : "Extension.url",
              "min" : 1,
              "max" : "1"
            },
            "type" : [
              {
                "code" : "uri"
              }
            ],
            "fixedUri" : "http://hl7.org/fhir/uv/cqm/StructureDefinition/cqm-populationBasis",
            "isModifier" : false,
            "isSummary" : false,
            "mapping" : [
              {
                "identity" : "rim",
                "map" : "N/A"
              }
            ]
          },
          {
            "id" : "Extension.value[x]",
            "path" : "Extension.value[x]",
            "short" : "Value of extension",
            "definition" : "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" : 0,
            "max" : "1",
            "base" : {
              "path" : "Extension.value[x]",
              "min" : 0,
              "max" : "1"
            },
            "type" : [
              {
                "code" : "code"
              },
              {
                "code" : "DataRequirement"
              }
            ],
            "constraint" : [
              {
                "key" : "ele-1",
                "severity" : "error",
                "human" : "All FHIR elements must have a @value or children",
                "expression" : "hasValue() or (children().count() > id.count())",
                "xpath" : "@value|f:*|h:div",
                "source" : "http://hl7.org/fhir/StructureDefinition/Element"
              }
            ],
            "isModifier" : false,
            "isSummary" : false,
            "binding" : {
              "strength" : "required",
              "description" : "The type of elements in the population",
              "valueSet" : "http://hl7.org/fhir/ValueSet/all-types"
            },
            "mapping" : [
              {
                "identity" : "rim",
                "map" : "N/A"
              }
            ]
          }
        ]
      },
      "differential" : {
        "element" : [
          {
            "id" : "Extension",
            "path" : "Extension",
            "short" : "What type of population",
            "definition" : "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" : "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" : 0,
            "max" : "*",
            "constraint" : [
              {
                "key" : "popBasis-1",
                "severity" : "error",
                "human" : "If DataRequirement.type is present, it may only contain the elements 'profile' and 'codeFilter'.",
                "expression" : "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())"
              }
            ]
          },
          {
            "id" : "Extension.url",
            "path" : "Extension.url",
            "type" : [
              {
                "code" : "uri"
              }
            ],
            "fixedUri" : "http://hl7.org/fhir/uv/cqm/StructureDefinition/cqm-populationBasis"
          },
          {
            "id" : "Extension.value[x]",
            "path" : "Extension.value[x]",
            "type" : [
              {
                "code" : "code"
              },
              {
                "code" : "DataRequirement"
              }
            ],
            "binding" : {
              "strength" : "required",
              "description" : "The type of elements in the population",
              "valueSet" : "http://hl7.org/fhir/ValueSet/all-types"
            }
          }
        ]
      }
    }