Structured Data Capture
4.0.0 - STU 4
Structured Data Capture
4.0.0 - STU 4
Structured Data Capture, published by HL7 International / FHIR Infrastructure. This guide is not an authorized publication; it is the continuous build for version 4.0.0 built by the FHIR (HL7® FHIR® Standard) CI Build. This version is based on the current content of https://github.com/HL7/sdc/ and changes regularly. See the Directory of published versions
| Official URL: http://hl7.org/fhir/uv/sdc/StructureDefinition/sdc-questionnaire-enableWhenExpression | Version: 4.0.0 | |||
| Standards status: Trial-use | Maturity Level: 4 | Computable Name: EnableWhenExpressionExtension | ||
| Other Identifiers: OID:2.16.840.1.113883.4.642.40.17.42.22 | ||||
An expression that returns a boolean value for whether to enable the item. If the expression does not resolve to a boolean, it is considered an error in the design of the Questionnaire. Form renderer behavior is undefined. Some tools may attempt to force the value to be a boolean (e.g. is it a non-empty collection, non-null, non-zero - if so, then true). Systems SHOULD present a warning to the user if a non-boolean valued expression result does not trigger an all-out error.
Context of Use
This extension may be used on the following element(s)
Questionnaire.item
ElementDefinition
Additional details on the use of this extension can be found on the Form Behavior page.
For information on how enableWhenExpression enables complex conditional logic, refer to the Expressions page - enableWhenExpression section.
Usage info
Usages:
You can also check for usages in the FHIR IG Statistics
Description of Profiles, Differentials, Snapshots, and how the XML and JSON presentations work.
This structure is derived from Extension
| Name | Flags | Card. | Type | Description & Constraints Filter:   |
|---|---|---|---|---|
  Extension |
0..1 | Extension | Expression for when to enable the item | |
  extension |
0..0 | |||
| url |
1..1 | uri | "http://hl7.org/fhir/uv/sdc/StructureDefinition/sdc-questionnaire-enableWhenExpression" | |
  value[x] |
C | 0..1 | Expression | Value of extension Constraints: sdc-inv1 |
| Documentation for this format | ||||
| Name | Flags | Card. | Type | Description & Constraints Filter: |
|---|---|---|---|---|
| Extension |
0..1 | Extension | Expression for when to enable the item | |
 id |
0..1 | string | Unique id for inter-element referencing | |
| extension |
0..0 | |||
| url |
1..1 | uri | "http://hl7.org/fhir/uv/sdc/StructureDefinition/sdc-questionnaire-enableWhenExpression" | |
| value[x] |
C | 0..1 | Expression | Value of extension Constraints: sdc-inv1 |
| Documentation for this format | ||||
This structure is derived from Extension
Summary
Simple Extension with the type Expression: An expression that returns a boolean value for whether to enable the item. If the expression does not resolve to a boolean, it is considered an error in the design of the Questionnaire. Form renderer behavior is undefined. Some tools may attempt to force the value to be a boolean (e.g. is it a non-empty collection, non-null, non-zero - if so, then true). Systems SHOULD present a warning to the user if a non-boolean valued expression result does not trigger an all-out error.
Maturity: 4
Differential View
This structure is derived from Extension
| Name | Flags | Card. | Type | Description & Constraints Filter: |
|---|---|---|---|---|
| Extension |
0..1 | Extension | Expression for when to enable the item | |
| extension |
0..0 | |||
| url |
1..1 | uri | "http://hl7.org/fhir/uv/sdc/StructureDefinition/sdc-questionnaire-enableWhenExpression" | |
| value[x] |
C | 0..1 | Expression | Value of extension Constraints: sdc-inv1 |
| Documentation for this format | ||||
Snapshot View
| Name | Flags | Card. | Type | Description & Constraints Filter: |
|---|---|---|---|---|
| Extension |
0..1 | Extension | Expression for when to enable the item | |
| id |
0..1 | string | Unique id for inter-element referencing | |
| extension |
0..0 | |||
| url |
1..1 | uri | "http://hl7.org/fhir/uv/sdc/StructureDefinition/sdc-questionnaire-enableWhenExpression" | |
| value[x] |
C | 0..1 | Expression | Value of extension Constraints: sdc-inv1 |
| Documentation for this format | ||||
This structure is derived from Extension
Summary
Simple Extension with the type Expression: An expression that returns a boolean value for whether to enable the item. If the expression does not resolve to a boolean, it is considered an error in the design of the Questionnaire. Form renderer behavior is undefined. Some tools may attempt to force the value to be a boolean (e.g. is it a non-empty collection, non-null, non-zero - if so, then true). Systems SHOULD present a warning to the user if a non-boolean valued expression result does not trigger an all-out error.
Maturity: 4
Other representations of profile: CSV, Excel, Schematron
| Id | Grade | Path(s) | Details | Requirements |
| 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() | |
| sdc-inv1 | error | Extension.value[x] | FHIR query language not allowed. : language!='application/x-fhir-query' |
IG © 2022+ HL7 International / FHIR Infrastructure. Package hl7.fhir.uv.sdc#4.0.0 based on FHIR 4.0.1. Generated 2025-09-18
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