Structured Data Capture
4.0.0 - STU 4 International flag

This page is part of the Structured Data Capture FHIR IG (v4.0.0: STU 4) based on FHIR (HL7® FHIR® Standard) R4. This is the current published version. For a full list of available versions, see the Directory of published versions

Extension: Initial Expression

Official URL: http://hl7.org/fhir/uv/sdc/StructureDefinition/sdc-questionnaire-initialExpression Version: 4.0.0
Standards status: Trial-use Active as of 2026-03-24 Maturity Level: 4 Computable Name: InitialExpressionExtension
Other Identifiers: OID:2.16.840.1.113883.4.642.40.17.42.28

Initial value for a question answer as determined by an evaluated expression.

Context of Use

Additional details on the use of this extension can be found on the Form Behavior, Questionnaire Population, and Data Extraction pages. For guidance on using initialExpression refer to the Expressions page - initialExpression section.

Usage info

Usages:

You can also check for usages in the FHIR IG Statistics

Formal Views of Extension Content

Description Differentials, Snapshots, and other representations.

NameFlagsCard.TypeDescription & Constraints    Filter: Filtersdoco
.. Extension 0..1 Extension Expression-determined initial value
... extension 0..0 Extension
... url 1..1 uri "http://hl7.org/fhir/uv/sdc/StructureDefinition/sdc-questionnaire-initialExpression"
... value[x] 0..1 Expression Value of extension

doco Documentation for this format
NameFlagsCard.TypeDescription & Constraints    Filter: Filtersdoco
.. Extension 0..1 Extension Expression-determined initial value
... id 0..1 string Unique id for inter-element referencing
... extension 0..0 Extension
Slice: Unordered, Open by value:url
... url 1..1 uri "http://hl7.org/fhir/uv/sdc/StructureDefinition/sdc-questionnaire-initialExpression"

doco Documentation for this format

Constraints

Id Grade Path(s) Description Expression
ele-1 error **ALL** elements All FHIR elements must have a @value or children hasValue() or (children().count() > id.count())
ext-1 error **ALL** extensions Must have either extensions or value[x], not both extension.exists() != value.exists()

Summary

Simple Extension with the type Expression: Initial value for a question answer as determined by an evaluated expression.

Maturity: 4

Differential ViewDifferential View

NameFlagsCard.TypeDescription & Constraints    Filter: Filtersdoco
.. Extension 0..1 Extension Expression-determined initial value
... extension 0..0 Extension
... url 1..1 uri "http://hl7.org/fhir/uv/sdc/StructureDefinition/sdc-questionnaire-initialExpression"
... value[x] 0..1 Expression Value of extension

doco Documentation for this format

Snapshot View

NameFlagsCard.TypeDescription & Constraints    Filter: Filtersdoco
.. Extension 0..1 Extension Expression-determined initial value
... id 0..1 string Unique id for inter-element referencing
... extension 0..0 Extension
Slice: Unordered, Open by value:url
... url 1..1 uri "http://hl7.org/fhir/uv/sdc/StructureDefinition/sdc-questionnaire-initialExpression"

doco Documentation for this format

Constraints

Id Grade Path(s) Description Expression
ele-1 error **ALL** elements All FHIR elements must have a @value or children hasValue() or (children().count() > id.count())
ext-1 error **ALL** extensions Must have either extensions or value[x], not both extension.exists() != value.exists()

Summary

Simple Extension with the type Expression: Initial value for a question answer as determined by an evaluated expression.

Maturity: 4

 

Other representations of profile: CSV, Excel, Schematron