HL7.FHIR.UV.EXTENSIONS\Resource Derivation Reference - 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: ResourceDerivationReference - Detailed Descriptions

Page standards status: Trial-use

Maturity Level: 2

Definitions for the derivation-reference extension.

Differential Elements Table
Key Elements Table
Snapshot Elements Table

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

0. Extension
Definition	References a location within a set of source text from which the discrete information described by this Resource/Element was extracted.
Short	References a location within a set of source text from which the discrete information described by this Resource/Element was extracted.
Invariants	der-1: Cannot have length if offset is missing. (`extension.where(url='length').exists() implies extension.where(url='offset').exists()`)
2. Extension.extension:reference
Slice Name	reference
Definition	References a location within a set of source text from which the discrete information described by this Resource/Element was extracted.
Short	Source reference.
Control	0..1
4. Extension.extension:reference.extension
Control	0..0
6. Extension.extension:reference.url
Fixed Value	`reference`
8. Extension.extension:reference.value[x]
Control	1..?
Type	Reference
[x] Note	SeeChoice of Data Typesfor further information about how to use [x]
10. Extension.extension:path
Slice Name	path
Definition	Corresponds to the element within the resource containing the text.
Short	Element containing text.
Comments	Follows the FHIRPath expression syntax used for OperationOutcome. If not present, then the resource must either be a Binary or a DocumentReference (with a single content element) and the content is the text represented by the instance or the attachment. If the DocumentReference has more than one 'content', then this path element SHALL be present to distinguish which repetition the derivation occurred from.
Control	0..1
12. Extension.extension:path.extension
Control	0..0
14. Extension.extension:path.url
Fixed Value	`path`
16. Extension.extension:path.value[x]
Control	1..?
Type	string
[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:offset
Slice Name	offset
Definition	Indicates the starting position (as a count of characters) within the text where the relevant derivation began.
Short	Starting position.
Control	0..1
Meaning if Missing	If not specified, the location at which derivation started is unknown.
20. Extension.extension:offset.extension
Control	0..0
22. Extension.extension:offset.url
Fixed Value	`offset`
24. Extension.extension:offset.value[x]
Control	1..?
Type	integer
[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.extension:length
Slice Name	length
Definition	Indicates the number of characters following the start position/beginning of the document that was used as part of the derivation process.
Short	Number of characters.
Control	0..1
Meaning if Missing	If not specified, the location at which derivation ended is unknown.
28. Extension.extension:length.extension
Control	0..0
30. Extension.extension:length.url
Fixed Value	`length`
32. Extension.extension:length.value[x]
Control	1..?
Type	integer
[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
34. Extension.url
Fixed Value	`http://hl7.org/fhir/StructureDefinition/derivation-reference`
36. Extension.value[x]
Control	0..0

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

0. Extension
Definition	References a location within a set of source text from which the discrete information described by this Resource/Element was extracted. Optional Extension Element - found in all resources.
Short	References a location within a set of source text from which the discrete information described by this Resource/Element was extracted.Optional Extensions Element
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()) der-1: Cannot have length if offset is missing. (`extension.where(url='length').exists() implies extension.where(url='offset').exists()`)
2. Extension.extension:reference
Slice Name	reference
Definition	References a location within a set of source text from which the discrete information described by this Resource/Element was extracted.
Short	Source reference.Additional content defined by implementations
Control	0..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())
4. Extension.extension:reference.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
6. Extension.extension:reference.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	`reference`
8. Extension.extension:reference.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	Reference, 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, code, string, oid, instant, ContactPoint, HumanName, Money, markdown, Ratio, Age, 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
Summary	false
Invariants	ele-1: All FHIR elements must have a @value or children (hasValue() or (children().count() > id.count()))
10. Extension.extension:path
Slice Name	path
Definition	Corresponds to the element within the resource containing the text.
Short	Element containing text.Additional content defined by implementations
Comments	Follows the FHIRPath expression syntax used for OperationOutcome. If not present, then the resource must either be a Binary or a DocumentReference (with a single content element) and the content is the text represented by the instance or the attachment. If the DocumentReference has more than one 'content', then this path element SHALL be present to distinguish which repetition the derivation occurred from.
Control	0..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())
12. Extension.extension:path.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
14. Extension.extension:path.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	`path`
16. Extension.extension:path.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	string, 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, code, 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()))
18. Extension.extension:offset
Slice Name	offset
Definition	Indicates the starting position (as a count of characters) within the text where the relevant derivation began.
Short	Starting position.Additional content defined by implementations
Control	0..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())
20. Extension.extension:offset.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
22. Extension.extension:offset.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	`offset`
24. Extension.extension:offset.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	integer, date, Meta, Address, Attachment, 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, code, 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()))
26. Extension.extension:length
Slice Name	length
Definition	Indicates the number of characters following the start position/beginning of the document that was used as part of the derivation process.
Short	Number of characters.Additional content defined by implementations
Control	0..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:length.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
30. Extension.extension:length.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	`length`
32. Extension.extension:length.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	integer, date, Meta, Address, Attachment, 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, code, 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()))
34. 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/derivation-reference`
36. 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	References a location within a set of source text from which the discrete information described by this Resource/Element was extracted.
Short	References a location within a set of source text from which the discrete information described by this Resource/Element was extracted.
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()`) der-1: Cannot have length if offset is missing. (`extension.where(url='length').exists() implies extension.where(url='offset').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	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`. The slices areUnordered and Open, and can be differentiated using the following discriminators: value @ url
6. Extension.extension:reference
Slice Name	reference
Definition	References a location within a set of source text from which the discrete information described by this Resource/Element was extracted.
Short	Source reference.
Control	0..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:reference.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:reference.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:reference.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	`reference`
14. Extension.extension:reference.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	Reference
[x] Note	SeeChoice of Data Typesfor further information about how to use [x]
Is Modifier	false
Summary	false
Invariants	ele-1: All FHIR elements must have a @value or children (`hasValue() or (children().count() > id.count())`)
16. Extension.extension:path
Slice Name	path
Definition	Corresponds to the element within the resource containing the text.
Short	Element containing text.
Comments	Follows the FHIRPath expression syntax used for OperationOutcome. If not present, then the resource must either be a Binary or a DocumentReference (with a single content element) and the content is the text represented by the instance or the attachment. If the DocumentReference has more than one 'content', then this path element SHALL be present to distinguish which repetition the derivation occurred from.
Control	0..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:path.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:path.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:path.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	`path`
24. Extension.extension:path.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	string
[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:offset
Slice Name	offset
Definition	Indicates the starting position (as a count of characters) within the text where the relevant derivation began.
Short	Starting position.
Control	0..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:offset.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:offset.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:offset.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	`offset`
34. Extension.extension:offset.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	integer
[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.extension:length
Slice Name	length
Definition	Indicates the number of characters following the start position/beginning of the document that was used as part of the derivation process.
Short	Number of characters.
Control	0..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()`)
38. Extension.extension:length.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
40. Extension.extension:length.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
42. Extension.extension:length.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	`length`
44. Extension.extension:length.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	integer
[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())`)
46. 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/derivation-reference`
48. Extension.value[x]
Definition	Changed: 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())`)