Release 4B
FoundationThis page is part of the FHIR Specification (v4.3.0: R4B - STU). The current version which supercedes this version is 5.0.0. For a full list of available versions, see the Directory of published versions 
. Page versions: R5 R4B R4
| Modeling and Methodology Work Group | Maturity Level: N/A | Standards Status: Informative |
Raw JSON (canonical form + also see JSON Format Specification)
StructureDefinition for Expression
{
"resourceType" : "StructureDefinition",
"id" : "Expression",
"text" : {
"status" : "generated",
"div" : "<div>!-- Snipped for Brevity --></div>"
},
"extension" : [{
"url" : "http://hl7.org/fhir/StructureDefinition/structuredefinition-standards-status",
"valueCode" : "trial-use"
}],
"url" : "http://hl7.org/fhir/StructureDefinition/Expression",
"version" : "4.3.0",
"name" : "Expression",
"status" : "draft",
"experimental" : false,
"date" : "2022-05-28T12:47:40+10:00",
"publisher" : "HL7 FHIR Standard",
"contact" : [{
"telecom" : [{
"system" : "url",
"value" : "http://hl7.org/fhir"
}]
}],
"description" : "Base StructureDefinition for Expression Type: A expression that is evaluated in a specified context and returns a value. The context of use of the expression must specify the context in which the expression is evaluated, and how the result of the expression is used.",
"fhirVersion" : "4.3.0",
"mapping" : [{
"identity" : "rim",
"uri" : "http://hl7.org/v3",
"name" : "RIM Mapping"
}],
"kind" : "complex-type",
"abstract" : false,
"type" : "Expression",
"baseDefinition" : "http://hl7.org/fhir/StructureDefinition/Element",
"derivation" : "specialization",
"snapshot" : {
"element" : [{
"id" : "Expression",
"extension" : [{
"url" : "http://hl7.org/fhir/StructureDefinition/structuredefinition-standards-status",
"valueCode" : "trial-use"
}],
"path" : "Expression",
"short" : "An expression that can be used to generate a value",
"definition" : "A expression that is evaluated in a specified context and returns a value. The context of use of the expression must specify the context in which the expression is evaluated, and how the result of the expression is used.",
"min" : 0,
"max" : "*",
"base" : {
"path" : "Expression",
"min" : 0,
"max" : "*"
},
"condition" : ["ele-1"],
"constraint" : [{
"key" : "ele-1",
"severity" : "error",
"human" : "All FHIR elements must have a @value or children unless an empty Parameters resource",
"expression" : "hasValue() or (children().count() > id.count()) or $this is Parameters",
"xpath" : "@value|f:*|h:div|self::f:Parameters",
"source" : "http://hl7.org/fhir/StructureDefinition/Element"
},
{
"key" : "exp-1",
"severity" : "error",
"human" : "An expression or a reference must be provided",
"expression" : "expression.exists() or reference.exists()",
"xpath" : "exists(f:expression) or exists(f:reference)",
"source" : "http://hl7.org/fhir/StructureDefinition/Expression"
}],
"isModifier" : false,
"mapping" : [{
"identity" : "rim",
"map" : "n/a"
}]
},
{
"id" : "Expression.id",
"path" : "Expression.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" : "id"
}],
"code" : "http://hl7.org/fhirpath/System.String"
}],
"isModifier" : false,
"isSummary" : false,
"mapping" : [{
"identity" : "rim",
"map" : "n/a"
}]
},
{
"id" : "Expression.extension",
"path" : "Expression.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" : "Expression.description",
"path" : "Expression.description",
"short" : "Natural language description of the condition",
"definition" : "A brief, natural language description of the condition that effectively communicates the intended semantics.",
"min" : 0,
"max" : "1",
"base" : {
"path" : "Expression.description",
"min" : 0,
"max" : "1"
},
"type" : [{
"code" : "string"
}],
"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" : true
},
{
"id" : "Expression.name",
"path" : "Expression.name",
"short" : "Short name assigned to expression for reuse",
"definition" : "A short name assigned to the expression to allow for multiple reuse of the expression in the context where it is defined.",
"min" : 0,
"max" : "1",
"base" : {
"path" : "Expression.name",
"min" : 0,
"max" : "1"
},
"type" : [{
"code" : "id"
}],
"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" : true
},
{
"id" : "Expression.language",
"path" : "Expression.language",
"short" : "text/cql | text/fhirpath | application/x-fhir-query | text/cql-identifier | text/cql-expression | etc.",
"definition" : "The media type of the language for the expression.",
"min" : 1,
"max" : "1",
"base" : {
"path" : "Expression.language",
"min" : 1,
"max" : "1"
},
"type" : [{
"code" : "code"
}],
"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" : true,
"binding" : {
"extension" : [{
"url" : "http://hl7.org/fhir/build/StructureDefinition/binding-definition",
"valueString" : "The media type of the expression language."
},
{
"url" : "http://hl7.org/fhir/StructureDefinition/elementdefinition-maxValueSet",
"valueCanonical" : "http://hl7.org/fhir/ValueSet/mimetypes"
},
{
"url" : "http://hl7.org/fhir/StructureDefinition/elementdefinition-bindingName",
"valueString" : "ExpressionLanguage"
}],
"strength" : "extensible",
"valueSet" : "http://hl7.org/fhir/ValueSet/expression-language"
}
},
{
"id" : "Expression.expression",
"path" : "Expression.expression",
"short" : "Expression in specified language",
"definition" : "An expression in the specified language that returns a value.",
"min" : 0,
"max" : "1",
"base" : {
"path" : "Expression.expression",
"min" : 0,
"max" : "1"
},
"type" : [{
"code" : "string"
}],
"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" : true
},
{
"id" : "Expression.reference",
"path" : "Expression.reference",
"short" : "Where the expression is found",
"definition" : "A URI that defines where the expression is found.",
"comment" : "If both a reference and an expression is found, the reference SHALL point to the same expression.",
"min" : 0,
"max" : "1",
"base" : {
"path" : "Expression.reference",
"min" : 0,
"max" : "1"
},
"type" : [{
"code" : "uri"
}],
"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" : true
}]
},
"differential" : {
"element" : [{
"id" : "Expression",
"extension" : [{
"url" : "http://hl7.org/fhir/StructureDefinition/structuredefinition-standards-status",
"valueCode" : "trial-use"
}],
"path" : "Expression",
"short" : "An expression that can be used to generate a value",
"definition" : "A expression that is evaluated in a specified context and returns a value. The context of use of the expression must specify the context in which the expression is evaluated, and how the result of the expression is used.",
"min" : 0,
"max" : "*",
"constraint" : [{
"key" : "exp-1",
"severity" : "error",
"human" : "An expression or a reference must be provided",
"expression" : "expression.exists() or reference.exists()",
"xpath" : "exists(f:expression) or exists(f:reference)",
"source" : "http://hl7.org/fhir/StructureDefinition/Expression"
}]
},
{
"id" : "Expression.description",
"path" : "Expression.description",
"short" : "Natural language description of the condition",
"definition" : "A brief, natural language description of the condition that effectively communicates the intended semantics.",
"min" : 0,
"max" : "1",
"type" : [{
"code" : "string"
}],
"isSummary" : true
},
{
"id" : "Expression.name",
"path" : "Expression.name",
"short" : "Short name assigned to expression for reuse",
"definition" : "A short name assigned to the expression to allow for multiple reuse of the expression in the context where it is defined.",
"min" : 0,
"max" : "1",
"type" : [{
"code" : "id"
}],
"isSummary" : true
},
{
"id" : "Expression.language",
"path" : "Expression.language",
"short" : "text/cql | text/fhirpath | application/x-fhir-query | text/cql-identifier | text/cql-expression | etc.",
"definition" : "The media type of the language for the expression.",
"min" : 1,
"max" : "1",
"type" : [{
"code" : "code"
}],
"isSummary" : true,
"binding" : {
"extension" : [{
"url" : "http://hl7.org/fhir/build/StructureDefinition/binding-definition",
"valueString" : "The media type of the expression language."
},
{
"url" : "http://hl7.org/fhir/StructureDefinition/elementdefinition-maxValueSet",
"valueCanonical" : "http://hl7.org/fhir/ValueSet/mimetypes"
},
{
"url" : "http://hl7.org/fhir/StructureDefinition/elementdefinition-bindingName",
"valueString" : "ExpressionLanguage"
}],
"strength" : "extensible",
"valueSet" : "http://hl7.org/fhir/ValueSet/expression-language"
}
},
{
"id" : "Expression.expression",
"path" : "Expression.expression",
"short" : "Expression in specified language",
"definition" : "An expression in the specified language that returns a value.",
"min" : 0,
"max" : "1",
"type" : [{
"code" : "string"
}],
"isSummary" : true
},
{
"id" : "Expression.reference",
"path" : "Expression.reference",
"short" : "Where the expression is found",
"definition" : "A URI that defines where the expression is found.",
"comment" : "If both a reference and an expression is found, the reference SHALL point to the same expression.",
"min" : 0,
"max" : "1",
"type" : [{
"code" : "uri"
}],
"isSummary" : true
}]
}
}
Usage note: every effort has been made to ensure that the examples are correct and useful, but they are not a normative part of the specification.
FHIR ®© HL7.org 2011+. FHIR Release 4B (v4.3.0) hl7.fhir.r4b.core#4.3.0 generated on Sat, May 28, 2022 12:53+1000.
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