Release 4 4B

This page is part of the FHIR Specification (v4.0.1: R4 (v4.3.0: R4B - Mixed Normative and STU ) in it's permanent home (it will always be available at this URL). ). 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 R4B R4

Extension: expression

Vocabulary Work Group   Maturity Level : 1 Informative Use Context : Any

URL for this extension: 


http://hl7.org/fhir/StructureDefinition/valueset-expression

Status: draft. Extension maintained by: HL7

An expression that provides an alternative definition of the content of the value set. There are two different ways to use this expression extension: If both an expression and a compose element is present, the compose is understood the make the same statement as the expression. If there is no compose, the expression is the only definition of the value set, and the value set can only be processed by a server that understands the expression syntax, it that is computable.

Comment :

The expression may be a reference or the actual expression, and ss expected to be a computable format (use the rules-text extension for a non-computable description).

Context of Use: Use on Element ID ValueSet

Extension Content

Summary

Name Flags Card. Type Description & Constraints doco
. . expression 0..1 Expression URL = http://hl7.org/fhir/StructureDefinition/valueset-expression
expression: An expression that provides an alternative definition of the content of the value set. There are two different ways to use this expression extension: If both an expression and a compose element is present, the compose is understood the make the same statement as the expression. If there is no compose, the expression is the only definition of the value set, and the value set can only be processed by a server that understands the expression syntax, it that is computable.


Use on Element ID ValueSet

doco Documentation for this format

Full Structure

Name Flags Card. Type Description & Constraints doco
. . extension 0..1 Extension URL = http://hl7.org/fhir/StructureDefinition/valueset-expression
expression: An expression that provides an alternative definition of the content of the value set. There are two different ways to use this expression extension: If both an expression and a compose element is present, the compose is understood the make the same statement as the expression. If there is no compose, the expression is the only definition of the value set, and the value set can only be processed by a server that understands the expression syntax, it that is computable.


Use on Element ID ValueSet
. . . extension I 0..0
. . . url 1..1 uri "http://hl7.org/fhir/StructureDefinition/valueset-expression"
. . . value[x] I 1..1 Expression Value of extension

doco Documentation for this format

XML Template 

<!-- expression -->doco

<extension xmlns="http://hl7.org/fhir"
     url="http://hl7.org/fhir/StructureDefinition/valueset-expression" >
  <!-- from Element: extension -->
 <</valueExpression>

 <valueExpression><!-- ?? 1..1 Expression Value of extension --></valueExpression>

</extension>

JSON Template 

{ // expression
  // from Element: extension
    "extension" : [ //  sliced by value:url  in the specified order, Open ]
    "url" : "http://hl7.org/fhir/StructureDefinition/valueset-expression", // R! 
    "

    "valueExpression" : { Expression } // C? R! Value of extension

  }

Summary

Name Flags Card. Type Description & Constraints doco
. . expression 0..1 Expression URL = http://hl7.org/fhir/StructureDefinition/valueset-expression
expression: An expression that provides an alternative definition of the content of the value set. There are two different ways to use this expression extension: If both an expression and a compose element is present, the compose is understood the make the same statement as the expression. If there is no compose, the expression is the only definition of the value set, and the value set can only be processed by a server that understands the expression syntax, it that is computable.


Use on Element ID ValueSet

doco Documentation for this format

Full Structure

Name Flags Card. Type Description & Constraints doco
. . extension 0..1 Extension URL = http://hl7.org/fhir/StructureDefinition/valueset-expression
expression: An expression that provides an alternative definition of the content of the value set. There are two different ways to use this expression extension: If both an expression and a compose element is present, the compose is understood the make the same statement as the expression. If there is no compose, the expression is the only definition of the value set, and the value set can only be processed by a server that understands the expression syntax, it that is computable.


Use on Element ID ValueSet
. . . extension I 0..0
. . . url 1..1 uri "http://hl7.org/fhir/StructureDefinition/valueset-expression"
. . . value[x] I 1..1 Expression Value of extension

doco Documentation for this format

XML Template 

<!-- expression -->doco

<extension xmlns="http://hl7.org/fhir"
     url="http://hl7.org/fhir/StructureDefinition/valueset-expression" >
  <!-- from Element: extension -->
 <</valueExpression>

 <valueExpression><!-- ?? 1..1 Expression Value of extension --></valueExpression>

</extension>

JSON Template 

{ // expression
  // from Element: extension
    "extension" : [ //  sliced by value:url  in the specified order, Open ]
    "url" : "http://hl7.org/fhir/StructureDefinition/valueset-expression", // R! 
    "

    "valueExpression" : { Expression } // C? R! Value of extension

  }

 

Constraints

  • ele-1 : All FHIR elements must have a @value or children unless an empty Parameters resource (xpath: @value|f:*|h:div @value|f:*|h:div|self::f:Parameters )
  • 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 )