Release 5 Preview #1

This page is part of the FHIR Specification (v4.2.0: R5 Preview #1). 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: R4B R4

Extension: Variable

FHIR Infrastructure Work Group

Maturity Level: 1

Informative

Use Context: Any

URL for this extension:

http://hl7.org/fhir/StructureDefinition/variable

Status: draft. Extension maintained by: Health Level Seven International (FHIR Infrastructure)

Variable specifying a logic to generate a variable for use in subsequent logic. The name of the variable will be added to FHIRPath's context when processing descendants of the element that contains this extension.

Comment:

Ordering of variable extension declarations is significant as variables declared in one repetition of this extension might be used in subsequent extension repetitions.

Context of Use: Use on Element ID Questionnaire, Element ID Questionnaire.item or Element ID Questionnaire.item.item

Summary

Name	Flags	Card.	Type	Description & Constraints
Variable		0..*	Expression	URL = http://hl7.org/fhir/StructureDefinition/variable Variable: Variable specifying a logic to generate a variable for use in subsequent logic. The name of the variable will be added to FHIRPath's context when processing descendants of the element that contains this extension. Use on Element ID Questionnaire, Element ID Questionnaire.item or Element ID Questionnaire.item.item
Documentation for this format

Full Structure

Name	Flags	Card.	Type	Description & Constraints
extension		0..*	Extension	URL = http://hl7.org/fhir/StructureDefinition/variable Variable: Variable specifying a logic to generate a variable for use in subsequent logic. The name of the variable will be added to FHIRPath's context when processing descendants of the element that contains this extension. Use on Element ID Questionnaire, Element ID Questionnaire.item or Element ID Questionnaire.item.item
extension	I	0..0
url		1..1	uri	"http://hl7.org/fhir/StructureDefinition/variable"
value[x]	I	1..1	Expression	Value of extension
Documentation for this format

XML Template

<!-- Variable -->

<extension xmlns="http://hl7.org/fhir"
     url="http://hl7.org/fhir/StructureDefinition/variable" >
  <!-- from Element: extension -->
 <valueExpression><!--  1..1 Expression Value of extension --></valueExpression>
</extension>

JSON Template

{ // Variable
  // from Element: extension
    "extension" : [ //  sliced by value:url  in the specified order, Open ]
    "url" : "http://hl7.org/fhir/StructureDefinition/variable", // R! 
    "valueExpression" : { Expression } // C? R! Value of extension
  }

Summary

Name	Flags	Card.	Type	Description & Constraints
Variable		0..*	Expression	URL = http://hl7.org/fhir/StructureDefinition/variable Variable: Variable specifying a logic to generate a variable for use in subsequent logic. The name of the variable will be added to FHIRPath's context when processing descendants of the element that contains this extension. Use on Element ID Questionnaire, Element ID Questionnaire.item or Element ID Questionnaire.item.item
Documentation for this format

Full Structure

Name	Flags	Card.	Type	Description & Constraints
extension		0..*	Extension	URL = http://hl7.org/fhir/StructureDefinition/variable Variable: Variable specifying a logic to generate a variable for use in subsequent logic. The name of the variable will be added to FHIRPath's context when processing descendants of the element that contains this extension. Use on Element ID Questionnaire, Element ID Questionnaire.item or Element ID Questionnaire.item.item
extension	I	0..0
url		1..1	uri	"http://hl7.org/fhir/StructureDefinition/variable"
value[x]	I	1..1	Expression	Value of extension
Documentation for this format

XML Template

<!-- Variable -->

<extension xmlns="http://hl7.org/fhir"
     url="http://hl7.org/fhir/StructureDefinition/variable" >
  <!-- from Element: extension -->
 <valueExpression><!--  1..1 Expression Value of extension --></valueExpression>
</extension>

JSON Template

{ // Variable
  // from Element: extension
    "extension" : [ //  sliced by value:url  in the specified order, Open ]
    "url" : "http://hl7.org/fhir/StructureDefinition/variable", // R! 
    "valueExpression" : { Expression } // C? R! Value of extension
  }

Constraints

ele-1: All FHIR elements must have a @value or children (xpath: @value|f:*|h:div)
ext-1: Must have either extensions or value[x], not both (xpath: exists(f:extension)!=exists(f:*[starts-with(local-name(.), 'value')]))
ele-1: On Extension.extension: All FHIR elements must have a @value or children (xpath on Extension.extension: @value|f:*|h:div)
ext-1: On Extension.extension: Must have either extensions or value[x], not both (xpath on Extension.extension: exists(f:extension)!=exists(f:*[starts-with(local-name(.), "value")]))
ele-1: On Extension.value[x]: All FHIR elements must have a @value or children (xpath on Extension.value[x]: @value|f:*|h:div)