HL7.FHIR.UV.EXTENSIONS\Version Specific Value - Definitions

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

Extension: VersionSpecificValue - Detailed Descriptions

Page standards status: Trial-use

Maturity Level: 1

Definitions for the version-specific-value extension.

Guidance on how to interpret the contents of this table can be found here

0. Extension
Definition	Provides an alternative value for the element carrying this extension is the correct value for a particular range of FHIR versions. Optional Extension Element - found in all resources.
Short	Value for other versionsOptional Extensions Element
Comments	This extension is found in contexts where a definition is applying to more than one version, usually defining extensions, and should only be used in context that clearly document how a cross-version definition is used
Control	0..*
Is Modifier	false
Invariants	ele-1: All FHIR elements must have a @value or children (hasValue() or (children().count() > id.count())) ext-1: Must have either extensions or value[x], not both (extension.exists() != value.exists())
2. Extension.extension
Definition	May be used to represent additional information that is not part of the basic definition of the element. To make the use of extensions safe and managable, there is a strict set of governance applied to the definition and use of extensions. Though any implementer can define an extension, there is a set of requirements that SHALL be met as part of the definition of the extension.
Short	Additional content defined by implementations
Comments	There can be no stigma associated with the use of extensions by any application, project, or standard - regardless of the institution or jurisdiction that uses or defines the extensions. The use of extensions is what allows the FHIR specification to retain a core level of simplicity for everyone.
Control	30..*
Type	Extension
Is Modifier	false
Summary	false
Alternate Names	extensions, user content
Invariants	ele-1: All FHIR elements must have a @value or children (hasValue() or (children().count() > id.count())) ext-1: Must have either extensions or value[x], not both (extension.exists() != value.exists())
Slicing	This element introduces a set of slices on `Extension.extension`. The slices areUnordered and Open, and can be differentiated using the following discriminators: value @ url
4. Extension.extension:value
Slice Name	value
Definition	Earliest FHIR version that the content is appropriate for.
Short	Starting VersionAdditional content defined by implementations
Control	10..1*
Type	Extension
Is Modifier	false
Summary	false
Invariants	ele-1: All FHIR elements must have a @value or children (hasValue() or (children().count() > id.count())) ext-1: Must have either extensions or value[x], not both (extension.exists() != value.exists())
6. Extension.extension:value.extension
Definition	An Extension May be used to represent additional information that is not part of the basic definition of the element. To make the use of extensions safe and managable, there is a strict set of governance applied to the definition and use of extensions. Though any implementer can define an extension, there is a set of requirements that SHALL be met as part of the definition of the extension.
Short	ExtensionAdditional content defined by implementations
Comments	There can be no stigma associated with the use of extensions by any application, project, or standard - regardless of the institution or jurisdiction that uses or defines the extensions. The use of extensions is what allows the FHIR specification to retain a core level of simplicity for everyone.
Control	0..0*
Type	Extension
Is Modifier	false
Summary	false
Alternate Names	extensions, user content
Invariants	ele-1: All FHIR elements must have a @value or children (hasValue() or (children().count() > id.count())) ext-1: Must have either extensions or value[x], not both (extension.exists() != value.exists())
Slicing	This element introduces a set of slices on `Extension.extension.extension`. The slices areUnordered and Open, and can be differentiated using the following discriminators: value @ url
8. Extension.extension:value.url
Definition	Source of the definition for the extension code - a logical name or a URL.
Short	identifies the meaning of the extension
Comments	The definition may point directly to a computable or human-readable definition of the extensibility codes, or it may be a logical URI as declared in some other specification. The definition SHALL be a URI for the Structure Definition defining the extension.
Control	1..1
Type	uri
Is Modifier	false
Primitive Value	This primitive element may be present, or absent, or replaced by an extension
XML Format	In the XML format, this property is represented as an attribute.
Summary	false
Fixed Value	`value`
10. Extension.extension:value.value[x]
Definition	Value of extension - must be one of a constrained set of the data types (see Extensibility for a list).
Short	Value of extension
Control	10..1 This element is affected by the following invariants: ext-1
Type	Choice of: string, code, integer, boolean, decimal, url, canonical, date, Meta, Address, Attachment, Count, DataRequirement, Dosage, uuid, Identifier, RatioRange, Coding, SampledData, id, positiveInt, Distance, Availability, integer64, Period, Duration, Range, RelatedArtifact, base64Binary, UsageContext, Timing, ExtendedContactDetail, CodeableConcept, ParameterDefinition, dateTime, oid, instant, ContactPoint, HumanName, Money, markdown, Ratio, Age, Reference, TriggerDefinition, Quantity, uri, Annotation, ContactDetail, Expression, CodeableReference, Signature, unsignedInt, time
[x] Note	SeeChoice of Data Typesfor further information about how to use [x]
Is Modifier	false
Primitive Value	This primitive element may be present, or absent, or replaced by an extension
Summary	false
Invariants	ele-1: All FHIR elements must have a @value or children (hasValue() or (children().count() > id.count()))
12. Extension.extension:startFhirVersion
Slice Name	startFhirVersion
Definition	Earliest FHIR version that the content is appropriate for.
Short	Starting VersionAdditional content defined by implementations
Control	10..1*
Type	Extension
Is Modifier	false
Summary	false
Invariants	ele-1: All FHIR elements must have a @value or children (hasValue() or (children().count() > id.count())) ext-1: Must have either extensions or value[x], not both (extension.exists() != value.exists())
14. Extension.extension:startFhirVersion.extension
Definition	An Extension May be used to represent additional information that is not part of the basic definition of the element. To make the use of extensions safe and managable, there is a strict set of governance applied to the definition and use of extensions. Though any implementer can define an extension, there is a set of requirements that SHALL be met as part of the definition of the extension.
Short	ExtensionAdditional content defined by implementations
Comments	There can be no stigma associated with the use of extensions by any application, project, or standard - regardless of the institution or jurisdiction that uses or defines the extensions. The use of extensions is what allows the FHIR specification to retain a core level of simplicity for everyone.
Control	0..0*
Type	Extension
Is Modifier	false
Summary	false
Alternate Names	extensions, user content
Invariants	ele-1: All FHIR elements must have a @value or children (hasValue() or (children().count() > id.count())) ext-1: Must have either extensions or value[x], not both (extension.exists() != value.exists())
Slicing	This element introduces a set of slices on `Extension.extension.extension`. The slices areUnordered and Open, and can be differentiated using the following discriminators: value @ url
16. Extension.extension:startFhirVersion.url
Definition	Source of the definition for the extension code - a logical name or a URL.
Short	identifies the meaning of the extension
Comments	The definition may point directly to a computable or human-readable definition of the extensibility codes, or it may be a logical URI as declared in some other specification. The definition SHALL be a URI for the Structure Definition defining the extension.
Control	1..1
Type	uri
Is Modifier	false
Primitive Value	This primitive element may be present, or absent, or replaced by an extension
XML Format	In the XML format, this property is represented as an attribute.
Summary	false
Fixed Value	`startFhirVersion`
18. Extension.extension:startFhirVersion.value[x]
Definition	Value of extension - must be one of a constrained set of the data types (see Extensibility for a list).
Short	Value of extension
Control	10..1 This element is affected by the following invariants: ext-1
Binding	The codes SHALL be taken from For codes, see MajorFHIRVersions (required to `http://hl7.org/fhir/ValueSet/major-fhir-version`) 1.0, 3.0, 4.0, 4.3, or 5.0
Type	code, date, Meta, Address, Attachment, integer, Count, DataRequirement, Dosage, uuid, Identifier, RatioRange, Coding, SampledData, id, positiveInt, Distance, Availability, integer64, Period, Duration, canonical, Range, RelatedArtifact, base64Binary, UsageContext, Timing, decimal, ExtendedContactDetail, CodeableConcept, ParameterDefinition, dateTime, string, oid, instant, ContactPoint, HumanName, Money, markdown, Ratio, Age, Reference, TriggerDefinition, Quantity, uri, url, Annotation, ContactDetail, boolean, Expression, CodeableReference, Signature, unsignedInt, time
[x] Note	SeeChoice of Data Typesfor further information about how to use [x]
Is Modifier	false
Primitive Value	This primitive element may be present, or absent, or replaced by an extension
Summary	false
Invariants	ele-1: All FHIR elements must have a @value or children (hasValue() or (children().count() > id.count()))
20. Extension.extension:endFhirVersion
Slice Name	endFhirVersion
Definition	Latest FHIR version that the content is appropriate for.
Short	Ending VersionAdditional content defined by implementations
Control	10..1*
Type	Extension
Is Modifier	false
Summary	false
Invariants	ele-1: All FHIR elements must have a @value or children (hasValue() or (children().count() > id.count())) ext-1: Must have either extensions or value[x], not both (extension.exists() != value.exists())
22. Extension.extension:endFhirVersion.extension
Definition	An Extension May be used to represent additional information that is not part of the basic definition of the element. To make the use of extensions safe and managable, there is a strict set of governance applied to the definition and use of extensions. Though any implementer can define an extension, there is a set of requirements that SHALL be met as part of the definition of the extension.
Short	ExtensionAdditional content defined by implementations
Comments	There can be no stigma associated with the use of extensions by any application, project, or standard - regardless of the institution or jurisdiction that uses or defines the extensions. The use of extensions is what allows the FHIR specification to retain a core level of simplicity for everyone.
Control	0..0*
Type	Extension
Is Modifier	false
Summary	false
Alternate Names	extensions, user content
Invariants	ele-1: All FHIR elements must have a @value or children (hasValue() or (children().count() > id.count())) ext-1: Must have either extensions or value[x], not both (extension.exists() != value.exists())
Slicing	This element introduces a set of slices on `Extension.extension.extension`. The slices areUnordered and Open, and can be differentiated using the following discriminators: value @ url
24. Extension.extension:endFhirVersion.url
Definition	Source of the definition for the extension code - a logical name or a URL.
Short	identifies the meaning of the extension
Comments	The definition may point directly to a computable or human-readable definition of the extensibility codes, or it may be a logical URI as declared in some other specification. The definition SHALL be a URI for the Structure Definition defining the extension.
Control	1..1
Type	uri
Is Modifier	false
Primitive Value	This primitive element may be present, or absent, or replaced by an extension
XML Format	In the XML format, this property is represented as an attribute.
Summary	false
Fixed Value	`endFhirVersion`
26. Extension.extension:endFhirVersion.value[x]
Definition	Value of extension - must be one of a constrained set of the data types (see Extensibility for a list).
Short	Value of extension
Control	10..1 This element is affected by the following invariants: ext-1
Binding	The codes SHALL be taken from For codes, see MajorFHIRVersions (required to `http://hl7.org/fhir/ValueSet/major-fhir-version`) 1.0, 3.0, 4.0, 4.3, or 5.0
Type	code, date, Meta, Address, Attachment, integer, Count, DataRequirement, Dosage, uuid, Identifier, RatioRange, Coding, SampledData, id, positiveInt, Distance, Availability, integer64, Period, Duration, canonical, Range, RelatedArtifact, base64Binary, UsageContext, Timing, decimal, ExtendedContactDetail, CodeableConcept, ParameterDefinition, dateTime, string, oid, instant, ContactPoint, HumanName, Money, markdown, Ratio, Age, Reference, TriggerDefinition, Quantity, uri, url, Annotation, ContactDetail, boolean, Expression, CodeableReference, Signature, unsignedInt, time
[x] Note	SeeChoice of Data Typesfor further information about how to use [x]
Is Modifier	false
Primitive Value	This primitive element may be present, or absent, or replaced by an extension
Summary	false
Invariants	ele-1: All FHIR elements must have a @value or children (hasValue() or (children().count() > id.count()))
28. Extension.url
Definition	Source of the definition for the extension code - a logical name or a URL.
Short	identifies the meaning of the extension
Comments	The definition may point directly to a computable or human-readable definition of the extensibility codes, or it may be a logical URI as declared in some other specification. The definition SHALL be a URI for the Structure Definition defining the extension.
Control	1..1
Type	uri
Is Modifier	false
XML Format	In the XML format, this property is represented as an attribute.
Summary	false
Fixed Value	`http://hl7.org/fhir/StructureDefinition/version-specific-value`
30. Extension.value[x]
Definition	Value of extension - must be one of a constrained set of the data types (see Extensibility for a list).
Short	Value of extension
Control	0..01 This element is affected by the following invariants: ext-1
Type	Choice of: base64Binary, boolean, canonical, code, date, dateTime, decimal, id, instant, integer, integer64, markdown, oid, positiveInt, string, time, unsignedInt, uri, url, uuid, Address, Age, Annotation, Attachment, CodeableConcept, CodeableReference, Coding, ContactPoint, Count, Distance, Duration, HumanName, Identifier, Money, Period, Quantity, Range, Ratio, RatioRange, Reference, SampledData, Signature, Timing, ContactDetail, DataRequirement, Expression, ParameterDefinition, RelatedArtifact, TriggerDefinition, UsageContext, Availability, ExtendedContactDetail, Dosage, Meta
Is Modifier	false
Primitive Value	This primitive element may be present, or absent, or replaced by an extension
Summary	false
Invariants	ele-1: All FHIR elements must have a @value or children (hasValue() or (children().count() > id.count()))

Guidance on how to interpret the contents of this table can be found here

0. Extension
Definition	Provides an alternative value for the element carrying this extension is the correct value for a particular range of FHIR versions.
Short	Value for other versions
Comments	This extension is found in contexts where a definition is applying to more than one version, usually defining extensions, and should only be used in context that clearly document how a cross-version definition is used
Control	0..*
2. Extension.extension:value
Slice Name	value
Definition	Earliest FHIR version that the content is appropriate for.
Short	Starting Version
Control	1..1
Type	Extension
4. Extension.extension:value.extension
Control	0..0
6. Extension.extension:value.url
Type	uri
Primitive Value	This primitive element may be present, or absent, or replaced by an extension
Fixed Value	`value`
8. Extension.extension:value.value[x]
Control	1..?
Type	Choice of: string, code, integer, boolean, decimal, url, canonical
[x] Note	SeeChoice of Data Typesfor further information about how to use [x]
Primitive Value	This primitive element may be present, or absent, or replaced by an extension
10. Extension.extension:startFhirVersion
Slice Name	startFhirVersion
Definition	Earliest FHIR version that the content is appropriate for.
Short	Starting Version
Control	1..1
Type	Extension
12. Extension.extension:startFhirVersion.extension
Control	0..0
14. Extension.extension:startFhirVersion.url
Type	uri
Primitive Value	This primitive element may be present, or absent, or replaced by an extension
Fixed Value	`startFhirVersion`
16. Extension.extension:startFhirVersion.value[x]
Control	1..?
Binding	The codes SHALL be taken from MajorFHIRVersions (required to `http://hl7.org/fhir/ValueSet/major-fhir-version`) 1.0, 3.0, 4.0, 4.3, or 5.0
Type	code
[x] Note	SeeChoice of Data Typesfor further information about how to use [x]
Primitive Value	This primitive element may be present, or absent, or replaced by an extension
18. Extension.extension:endFhirVersion
Slice Name	endFhirVersion
Definition	Latest FHIR version that the content is appropriate for.
Short	Ending Version
Control	1..1
Type	Extension
20. Extension.extension:endFhirVersion.extension
Control	0..0
22. Extension.extension:endFhirVersion.url
Type	uri
Primitive Value	This primitive element may be present, or absent, or replaced by an extension
Fixed Value	`endFhirVersion`
24. Extension.extension:endFhirVersion.value[x]
Control	1..?
Binding	The codes SHALL be taken from MajorFHIRVersions (required to `http://hl7.org/fhir/ValueSet/major-fhir-version`) 1.0, 3.0, 4.0, 4.3, or 5.0
Type	code
[x] Note	SeeChoice of Data Typesfor further information about how to use [x]
Primitive Value	This primitive element may be present, or absent, or replaced by an extension
26. Extension.url
Fixed Value	`http://hl7.org/fhir/StructureDefinition/version-specific-value`
28. Extension.value[x]
Control	0..0

Guidance on how to interpret the contents of this table can be found here

0. Extension
Definition	Provides an alternative value for the element carrying this extension is the correct value for a particular range of FHIR versions.
Short	Value for other versions
Comments	This extension is found in contexts where a definition is applying to more than one version, usually defining extensions, and should only be used in context that clearly document how a cross-version definition is used
Control	0..*
Is Modifier	false
Invariants	ele-1: All FHIR elements must have a @value or children (`hasValue() or (children().count() > id.count())`) ext-1: Must have either extensions or value[x], not both (`extension.exists() != value.exists()`)
2. Extension.id
Definition	Unique id for the element within a resource (for internal references). This may be any string value that does not contain spaces.
Short	Unique id for inter-element referencing
Control	0..1 This element is affected by the following invariants: ele-1
Type	id
Is Modifier	false
XML Format	In the XML format, this property is represented as an attribute.
Summary	false
4. Extension.extension
Definition	May be used to represent additional information that is not part of the basic definition of the element. To make the use of extensions safe and managable, there is a strict set of governance applied to the definition and use of extensions. Though any implementer can define an extension, there is a set of requirements that SHALL be met as part of the definition of the extension.
Short	Additional content defined by implementations
Comments	There can be no stigma associated with the use of extensions by any application, project, or standard - regardless of the institution or jurisdiction that uses or defines the extensions. The use of extensions is what allows the FHIR specification to retain a core level of simplicity for everyone.
Control	3..*
Type	Extension
Is Modifier	false
Summary	false
Alternate Names	extensions, user content
Invariants	ele-1: All FHIR elements must have a @value or children (`hasValue() or (children().count() > id.count())`) ext-1: Must have either extensions or value[x], not both (`extension.exists() != value.exists()`)
Slicing	This element introduces a set of slices on `Extension.extension`. The slices areUnordered and Open, and can be differentiated using the following discriminators: value @ url
6. Extension.extension:value
Slice Name	value
Definition	Earliest FHIR version that the content is appropriate for.
Short	Starting Version
Control	1..1
Type	Extension
Is Modifier	false
Summary	false
Invariants	ele-1: All FHIR elements must have a @value or children (`hasValue() or (children().count() > id.count())`) ext-1: Must have either extensions or value[x], not both (`extension.exists() != value.exists()`)
8. Extension.extension:value.id
Definition	Unique id for the element within a resource (for internal references). This may be any string value that does not contain spaces.
Short	Unique id for inter-element referencing
Control	0..1 This element is affected by the following invariants: ele-1
Type	id
Is Modifier	false
XML Format	In the XML format, this property is represented as an attribute.
Summary	false
10. Extension.extension:value.extension
Definition	An Extension
Short	Extension
Control	0..0
Type	Extension
Is Modifier	false
Summary	false
Invariants	ele-1: All FHIR elements must have a @value or children (`hasValue() or (children().count() > id.count())`) ext-1: Must have either extensions or value[x], not both (`extension.exists() != value.exists()`)
Slicing	This element introduces a set of slices on `Extension.extension.extension`. The slices areUnordered and Open, and can be differentiated using the following discriminators: value @ url
12. Extension.extension:value.url
Definition	Source of the definition for the extension code - a logical name or a URL.
Short	identifies the meaning of the extension
Comments	The definition may point directly to a computable or human-readable definition of the extensibility codes, or it may be a logical URI as declared in some other specification. The definition SHALL be a URI for the Structure Definition defining the extension.
Control	1..1
Type	uri
Is Modifier	false
Primitive Value	This primitive element may be present, or absent, or replaced by an extension
XML Format	In the XML format, this property is represented as an attribute.
Summary	false
Fixed Value	`value`
14. Extension.extension:value.value[x]
Definition	Value of extension - must be one of a constrained set of the data types (see Extensibility for a list).
Short	Value of extension
Control	1..1 This element is affected by the following invariants: ext-1
Type	Choice of: string, code, integer, boolean, decimal, url, canonical
[x] Note	SeeChoice of Data Typesfor further information about how to use [x]
Is Modifier	false
Primitive Value	This primitive element may be present, or absent, or replaced by an extension
Summary	false
Invariants	ele-1: All FHIR elements must have a @value or children (`hasValue() or (children().count() > id.count())`)
16. Extension.extension:startFhirVersion
Slice Name	startFhirVersion
Definition	Earliest FHIR version that the content is appropriate for.
Short	Starting Version
Control	1..1
Type	Extension
Is Modifier	false
Summary	false
Invariants	ele-1: All FHIR elements must have a @value or children (`hasValue() or (children().count() > id.count())`) ext-1: Must have either extensions or value[x], not both (`extension.exists() != value.exists()`)
18. Extension.extension:startFhirVersion.id
Definition	Unique id for the element within a resource (for internal references). This may be any string value that does not contain spaces.
Short	Unique id for inter-element referencing
Control	0..1 This element is affected by the following invariants: ele-1
Type	id
Is Modifier	false
XML Format	In the XML format, this property is represented as an attribute.
Summary	false
20. Extension.extension:startFhirVersion.extension
Definition	An Extension
Short	Extension
Control	0..0
Type	Extension
Is Modifier	false
Summary	false
Invariants	ele-1: All FHIR elements must have a @value or children (`hasValue() or (children().count() > id.count())`) ext-1: Must have either extensions or value[x], not both (`extension.exists() != value.exists()`)
Slicing	This element introduces a set of slices on `Extension.extension.extension`. The slices areUnordered and Open, and can be differentiated using the following discriminators: value @ url
22. Extension.extension:startFhirVersion.url
Definition	Source of the definition for the extension code - a logical name or a URL.
Short	identifies the meaning of the extension
Comments	The definition may point directly to a computable or human-readable definition of the extensibility codes, or it may be a logical URI as declared in some other specification. The definition SHALL be a URI for the Structure Definition defining the extension.
Control	1..1
Type	uri
Is Modifier	false
Primitive Value	This primitive element may be present, or absent, or replaced by an extension
XML Format	In the XML format, this property is represented as an attribute.
Summary	false
Fixed Value	`startFhirVersion`
24. Extension.extension:startFhirVersion.value[x]
Definition	Value of extension - must be one of a constrained set of the data types (see Extensibility for a list).
Short	Value of extension
Control	1..1 This element is affected by the following invariants: ext-1
Binding	The codes SHALL be taken from MajorFHIRVersions (required to `http://hl7.org/fhir/ValueSet/major-fhir-version`) 1.0, 3.0, 4.0, 4.3, or 5.0
Type	code
[x] Note	SeeChoice of Data Typesfor further information about how to use [x]
Is Modifier	false
Primitive Value	This primitive element may be present, or absent, or replaced by an extension
Summary	false
Invariants	ele-1: All FHIR elements must have a @value or children (`hasValue() or (children().count() > id.count())`)
26. Extension.extension:endFhirVersion
Slice Name	endFhirVersion
Definition	Latest FHIR version that the content is appropriate for.
Short	Ending Version
Control	1..1
Type	Extension
Is Modifier	false
Summary	false
Invariants	ele-1: All FHIR elements must have a @value or children (`hasValue() or (children().count() > id.count())`) ext-1: Must have either extensions or value[x], not both (`extension.exists() != value.exists()`)
28. Extension.extension:endFhirVersion.id
Definition	Unique id for the element within a resource (for internal references). This may be any string value that does not contain spaces.
Short	Unique id for inter-element referencing
Control	0..1 This element is affected by the following invariants: ele-1
Type	id
Is Modifier	false
XML Format	In the XML format, this property is represented as an attribute.
Summary	false
30. Extension.extension:endFhirVersion.extension
Definition	An Extension
Short	Extension
Control	0..0
Type	Extension
Is Modifier	false
Summary	false
Invariants	ele-1: All FHIR elements must have a @value or children (`hasValue() or (children().count() > id.count())`) ext-1: Must have either extensions or value[x], not both (`extension.exists() != value.exists()`)
Slicing	This element introduces a set of slices on `Extension.extension.extension`. The slices areUnordered and Open, and can be differentiated using the following discriminators: value @ url
32. Extension.extension:endFhirVersion.url
Definition	Source of the definition for the extension code - a logical name or a URL.
Short	identifies the meaning of the extension
Comments	The definition may point directly to a computable or human-readable definition of the extensibility codes, or it may be a logical URI as declared in some other specification. The definition SHALL be a URI for the Structure Definition defining the extension.
Control	1..1
Type	uri
Is Modifier	false
Primitive Value	This primitive element may be present, or absent, or replaced by an extension
XML Format	In the XML format, this property is represented as an attribute.
Summary	false
Fixed Value	`endFhirVersion`
34. Extension.extension:endFhirVersion.value[x]
Definition	Value of extension - must be one of a constrained set of the data types (see Extensibility for a list).
Short	Value of extension
Control	1..1 This element is affected by the following invariants: ext-1
Binding	The codes SHALL be taken from MajorFHIRVersions (required to `http://hl7.org/fhir/ValueSet/major-fhir-version`) 1.0, 3.0, 4.0, 4.3, or 5.0
Type	code
[x] Note	SeeChoice of Data Typesfor further information about how to use [x]
Is Modifier	false
Primitive Value	This primitive element may be present, or absent, or replaced by an extension
Summary	false
Invariants	ele-1: All FHIR elements must have a @value or children (`hasValue() or (children().count() > id.count())`)
36. Extension.url
Definition	Source of the definition for the extension code - a logical name or a URL.
Short	identifies the meaning of the extension
Comments	The definition may point directly to a computable or human-readable definition of the extensibility codes, or it may be a logical URI as declared in some other specification. The definition SHALL be a URI for the Structure Definition defining the extension.
Control	1..1
Type	uri
Is Modifier	false
XML Format	In the XML format, this property is represented as an attribute.
Summary	false
Fixed Value	`http://hl7.org/fhir/StructureDefinition/version-specific-value`
38. Extension.value[x]
Definition	Value of extension - must be one of a constrained set of the data types (see Extensibility for a list).
Short	Value of extension
Control	0..0 This element is affected by the following invariants: ext-1
Type	Choice of: base64Binary, boolean, canonical, code, date, dateTime, decimal, id, instant, integer, integer64, markdown, oid, positiveInt, string, time, unsignedInt, uri, url, uuid, Address, Age, Annotation, Attachment, CodeableConcept, CodeableReference, Coding, ContactPoint, Count, Distance, Duration, HumanName, Identifier, Money, Period, Quantity, Range, Ratio, RatioRange, Reference, SampledData, Signature, Timing, ContactDetail, DataRequirement, Expression, ParameterDefinition, RelatedArtifact, TriggerDefinition, UsageContext, Availability, ExtendedContactDetail, Dosage, Meta
Is Modifier	false
Primitive Value	This primitive element may be present, or absent, or replaced by an extension
Summary	false
Invariants	ele-1: All FHIR elements must have a @value or children (`hasValue() or (children().count() > id.count())`)