FHIR Extensions Pack, published by HL7 International / FHIR Infrastructure. This guide is not an authorized publication; it is the continuous build for version 5.2.0-ballot built by the FHIR (HL7® FHIR® Standard) CI Build. This version is based on the current content of https://github.com/HL7/fhir-extensions/ and changes regularly. See the Directory of published versions

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Extension: Target Constraint

Specifies a constraint that is enforced on instantiated (or target) resources. This extension can be applied to definitional resources (such as ActivityDefinition or Measure) and indicates that the constraint should be enforced on resources that are instantiated from the definition. For example, this extension can be used to define a constraint such as numerator count must be less than or equal to denominator count.

This extension allows constraints to be specified as part of definitional resources as an alternative to having to define a profile to enforce the constraint.

Context of Use

This extension may be used on the following element(s):

• Element ID: ActivityDefinition
• Element ID: ActivityDefinition.participant
• Element ID: ActivityDefinition.dosage
• Element ID: Measure
• Element ID: Measure.group
• Element ID: Measure.group.population
• Element ID: Measure.group.stratifier
• Element ID: Measure.supplementalData
• Element ID: PlanDefinition
• Element ID: PlanDefinition.goal
• Element ID: PlanDefinition.goal.target
• Element ID: PlanDefinition.actor
• Element ID: PlanDefinition.action
• Element ID: Questionnaire
• Element ID: Questionnaire.item

Usage info

Usage:

• This Extension is not used by any profiles in this Implementation Guide

Formal Views of Extension Content

Description of Profiles, Differentials, Snapshots, and how the XML and JSON presentations work.

• Text Summary
• Differential Table
• Snapshot Table
• All

This structure is derived from Extension

Summary

Complex Extension: Specifies a constraint that is enforced on instantiated (or target) resources. This extension can be applied to definitional resources (such as ActivityDefinition or Measure) and indicates that the constraint should be enforced on resources that are instantiated from the definition. For example, this extension can be used to define a constraint such as numerator count must be less than or equal to denominator count.

• key: id: A unique identifier for the invariant (unique in the context of the resource).
• requirements: markdown: A brief description of why the constraint is necessary or appropriate.
• severity: code: Whether the constraint indicates an error condition or a warning.
• expression: Expression: An expression providing a formal representation of the invariant condition.
• human: string: A free text expression of the rule to display to the user if the rule is violated.
• location: string: Relative paths to the elements this rule is enforced against.

Maturity: 2

This structure is derived from Extension

Name	Flags	Card.	Type	Description & Constraints
Extension		0..*	Extension	A constraint on the target resource
Slices for extension				Content/Rules for all slices
extension:key		1..1	Extension	Unique identifier
extension		0..0
url		1..1	uri	"key"
value[x]		1..1	id	Value of extension
extension:requirements		0..1	Extension	Why the constraint is defined
extension		0..0
url		1..1	uri	"requirements"
value[x]		1..1	markdown	Value of extension
extension:severity		1..1	Extension	error | warning
extension		0..0
url		1..1	uri	"severity"
value[x]		1..1	code	Value of extension Binding: ConstraintSeverity (required)
extension:expression		1..1	Extension	The invariant expression
extension		0..0
url		1..1	uri	"expression"
value[x]		1..1	Expression	Value of extension
extension:human		1..1	Extension	Human-readable rule
extension		0..0
url		1..1	uri	"human"
value[x]		1..1	string	Value of extension
extension:location		0..*	Extension	Relative path to elements
extension		0..0
url		1..1	uri	"location"
value[x]		1..1	string	Value of extension
url		1..1	uri	"http://hl7.org/fhir/StructureDefinition/targetConstraint"
value[x]		0..0
Documentation for this format

Name	Flags	Card.	Type	Description & Constraints
Extension		0..*	Extension	A constraint on the target resource
id		0..1	id	Unique id for inter-element referencing
Slices for extension		4..*	Extension	Additional content defined by implementations Slice: Unordered, Open by value:url
extension:key		1..1	Extension	Unique identifier
id		0..1	id	Unique id for inter-element referencing
extension		0..0
url		1..1	uri	"key"
value[x]		1..1	id	Value of extension
extension:requirements		0..1	Extension	Why the constraint is defined
id		0..1	id	Unique id for inter-element referencing
extension		0..0
url		1..1	uri	"requirements"
value[x]		1..1	markdown	Value of extension
extension:severity		1..1	Extension	error | warning
id		0..1	id	Unique id for inter-element referencing
extension		0..0
url		1..1	uri	"severity"
value[x]		1..1	code	Value of extension Binding: ConstraintSeverity (required)
extension:expression		1..1	Extension	The invariant expression
id		0..1	id	Unique id for inter-element referencing
extension		0..0
url		1..1	uri	"expression"
value[x]		1..1	Expression	Value of extension
extension:human		1..1	Extension	Human-readable rule
id		0..1	id	Unique id for inter-element referencing
extension		0..0
url		1..1	uri	"human"
value[x]		1..1	string	Value of extension
extension:location		0..*	Extension	Relative path to elements
id		0..1	id	Unique id for inter-element referencing
extension		0..0
url		1..1	uri	"location"
value[x]		1..1	string	Value of extension
url		1..1	uri	"http://hl7.org/fhir/StructureDefinition/targetConstraint"
Documentation for this format

This structure is derived from Extension

Summary

Complex Extension: Specifies a constraint that is enforced on instantiated (or target) resources. This extension can be applied to definitional resources (such as ActivityDefinition or Measure) and indicates that the constraint should be enforced on resources that are instantiated from the definition. For example, this extension can be used to define a constraint such as numerator count must be less than or equal to denominator count.

• key: id: A unique identifier for the invariant (unique in the context of the resource).
• requirements: markdown: A brief description of why the constraint is necessary or appropriate.
• severity: code: Whether the constraint indicates an error condition or a warning.
• expression: Expression: An expression providing a formal representation of the invariant condition.
• human: string: A free text expression of the rule to display to the user if the rule is violated.
• location: string: Relative paths to the elements this rule is enforced against.

Maturity: 2

Differential View

This structure is derived from Extension

Name	Flags	Card.	Type	Description & Constraints
Extension		0..*	Extension	A constraint on the target resource
Slices for extension				Content/Rules for all slices
extension:key		1..1	Extension	Unique identifier
extension		0..0
url		1..1	uri	"key"
value[x]		1..1	id	Value of extension
extension:requirements		0..1	Extension	Why the constraint is defined
extension		0..0
url		1..1	uri	"requirements"
value[x]		1..1	markdown	Value of extension
extension:severity		1..1	Extension	error | warning
extension		0..0
url		1..1	uri	"severity"
value[x]		1..1	code	Value of extension Binding: ConstraintSeverity (required)
extension:expression		1..1	Extension	The invariant expression
extension		0..0
url		1..1	uri	"expression"
value[x]		1..1	Expression	Value of extension
extension:human		1..1	Extension	Human-readable rule
extension		0..0
url		1..1	uri	"human"
value[x]		1..1	string	Value of extension
extension:location		0..*	Extension	Relative path to elements
extension		0..0
url		1..1	uri	"location"
value[x]		1..1	string	Value of extension
url		1..1	uri	"http://hl7.org/fhir/StructureDefinition/targetConstraint"
value[x]		0..0
Documentation for this format

Snapshot View

Name	Flags	Card.	Type	Description & Constraints
Extension		0..*	Extension	A constraint on the target resource
id		0..1	id	Unique id for inter-element referencing
Slices for extension		4..*	Extension	Additional content defined by implementations Slice: Unordered, Open by value:url
extension:key		1..1	Extension	Unique identifier
id		0..1	id	Unique id for inter-element referencing
extension		0..0
url		1..1	uri	"key"
value[x]		1..1	id	Value of extension
extension:requirements		0..1	Extension	Why the constraint is defined
id		0..1	id	Unique id for inter-element referencing
extension		0..0
url		1..1	uri	"requirements"
value[x]		1..1	markdown	Value of extension
extension:severity		1..1	Extension	error | warning
id		0..1	id	Unique id for inter-element referencing
extension		0..0
url		1..1	uri	"severity"
value[x]		1..1	code	Value of extension Binding: ConstraintSeverity (required)
extension:expression		1..1	Extension	The invariant expression
id		0..1	id	Unique id for inter-element referencing
extension		0..0
url		1..1	uri	"expression"
value[x]		1..1	Expression	Value of extension
extension:human		1..1	Extension	Human-readable rule
id		0..1	id	Unique id for inter-element referencing
extension		0..0
url		1..1	uri	"human"
value[x]		1..1	string	Value of extension
extension:location		0..*	Extension	Relative path to elements
id		0..1	id	Unique id for inter-element referencing
extension		0..0
url		1..1	uri	"location"
value[x]		1..1	string	Value of extension
url		1..1	uri	"http://hl7.org/fhir/StructureDefinition/targetConstraint"
Documentation for this format

Other representations of profile: CSV, Excel, Schematron

Terminology Bindings

Constraints

R4B

The extension is unchanged in R4B

R4

The extension is unchanged in R4

R3

The extension is represented a little differently in R3:

• Replace the type Expression with a set of extensions for the content of the type along with the _datatype extension
• Note: Extensions that have been modified for R3 are still draft while real-world experience is collected

Name	Flags	Card.	Type	Description & Constraints
Extension		0..*	Extension	A constraint on the target resource
Slices for extension				Content/Rules for all slices
extension:key		1..1	Extension	Unique identifier
extension		0 .. 0
url		1 .. 1	uri	"key"
value[x]		1.. 1	id	Value of extension
extension:requirements		0..1	Extension	Why the constraint is defined
extension		0 .. 0
url		1 .. 1	uri	"requirements"
value[x]		1.. 1	markdown	Value of extension
extension:severity		1..1	Extension	error | warning
extension		0 .. 0
url		1 .. 1	uri	"severity"
value[x]		1.. 1	code	Value of extension Binding: ConstraintSeverity ( required )
extension:expression		1..1	Extension	The invariant expression
Slices for extension		0 ..*	Extension	Extension Slice: Unordered, Open by value:url
extension:_datatype		1..1	(Complex)	DataType name 'Expression' from R5 URL: http://hl7.org/fhir/StructureDefinition/_datatype
value[x]		1.. 1	string	Value of extension Fixed Value: Expression
extension:description		0..1	Extension	Natural language description of the condition
extension		0 .. 0
url		1 .. 1	uri	"description"
value[x]		1.. 1	string	Value of extension
extension:name		0..1	Extension	Short name assigned to expression for reuse
extension		0 .. 0
url		1 .. 1	uri	"name"
value[x]		1.. 1	code	Value of extension
extension:language		0..1	Extension	text/cql | text/fhirpath | application/x-fhir-query | etc.
extension		0 .. 0
url		1 .. 1	uri	"language"
value[x]		1.. 1	code	Value of extension Binding: ExpressionLanguage ( extensible ): The media type of the expression language. Additional Bindings Purpose MimeTypes Max Binding
extension:expression		0..1	Extension	Expression in specified language
extension		0 .. 0
url		1 .. 1	uri	"expression"
value[x]		1.. 1	string	Value of extension
extension:reference		0..1	Extension	Where the expression is found
extension		0 .. 0
url		1 .. 1	uri	"reference"
value[x]		1.. 1	uri	Value of extension
url		1 .. 1	uri	"expression"
value[x]		0 .. 0
extension:human		1..1	Extension	Human-readable rule
extension		0 .. 0
url		1 .. 1	uri	"human"
value[x]		1.. 1	string	Value of extension
extension:location		0..*	Extension	Relative path to elements
extension		0 .. 0
url		1 .. 1	uri	"location"
value[x]		1.. 1	string	Value of extension
url		1 .. 1	uri	"http://hl7.org/fhir/StructureDefinition/targetConstraint"
value[x]		0 .. 0
Documentation for this format

Notes:

"url":"http://example.org/Questionnaire/abc",
...
"linkId":"q1",
"text": "Question 1",
{ 
    "key": "seq-dt", 
    "severity": "error", 
    "expression" : "item.where(linkId='acc-date').answer.first().trace('acc-date') < %resource.authored.trace('authored')", 
    "human": "The accident date must be before the completion date of the form", 
    "location": "item.where(linkId='acc-date').answer.first()" 
}

{
  "severity": "error",
  "code": "Invariant",
  "details": {
    "coding": [{
      "system": "http://example.org/Questionnaire/abc", 
      "code" : "seq-dt", 
      "display": "The accident date must be before the review date"
    }],
    "text":"Question 1: The accident date must be before the completion date"
  },
  "diagnostics": "item.where(linkId='acc-date').answer.first().trace('acc-date') <  %resource.authored.trace('authored') acc-date: 2024-03-17; authored: 2024-02-01",
  "expression": ["QuestionnaireResponse.item[0].item[1].answer[0].value[0]"]
}

Search Parameters for this Extension

(none found)