FHIR Extensions Pack
5.2.0-ballot - 5.2.0 Ballot - September 2024) International flag

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: AlternateCanonical - Detailed Descriptions

Page standards status: Trial-use Maturity Level: 2

Definitions for the alternate-canonical extension.

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

0. Extension
Definition

icon Changed:

Used with inter-version extensions where the element being referenced by inter-version extension is of type 'canonical' and includes a reference to a resource whose canonical URL is different in the referencing version than it is in the FHIR version where the element was defined. E.g. if an R5 implementation were using inter-version extensions to support an element that referenced Bar, when in R7, the url would have been .../Foo. In this situation, the canonical element would have no value and would instead have an extension that referred to the canonical URL of the '../Bar' resource (which would technically not be supported in R7, but is appropriate in R5).

ShortAlternative reference (target type is wrong)
Control0..1
2. Extension.extension
Control0..0
4. Extension.url
Fixed Valuehttp://hl7.org/fhir/StructureDefinition/alternate-canonical
6. Extension.value[x]
Control1..?
Typecanonical(CanonicalResource), date, Meta, Address, Attachment, integer, Count, DataRequirement, Dosage, uuid, Identifier, RatioRange, Coding, SampledData, id, positiveInt, Distance, Availability, integer64, Period, Duration, 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] NoteSeeChoice of Data Typesfor further information about how to use [x]
Primitive ValueThis primitive element may be present, or absent, or replaced by an extension

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

0. Extension
Definition

Used with inter-version extensions where the element being referenced by inter-version extension is of type 'canonical' and includes a reference to a resource whose canonical URL is different in the referencing version than it is in the FHIR version where the element was defined. E.g. if an R5 implementation were using inter-version extensions to support an element that referenced Bar, when in R7, the url would have been .../Foo. In this situation, the canonical element would have no value and would instead have an extension that referred to the canonical URL of the '../Bar' resource (which would technically not be supported in R7, but is appropriate in R5).


Optional Extension Element - found in all resources.

ShortAlternative reference (target type is wrong)Optional Extensions Element
Control0..1*
Is Modifierfalse
Invariantsele-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

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.

ShortExtensionAdditional 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.

Control0..0*
TypeExtension
Is Modifierfalse
Summaryfalse
Alternate Namesextensions, user content
Invariantsele-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())
SlicingThis 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.url
    Definition

    Source of the definition for the extension code - a logical name or a URL.

    Shortidentifies 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.

    Control1..1
    Typeuri
    Is Modifierfalse
    XML FormatIn the XML format, this property is represented as an attribute.
    Summaryfalse
    Fixed Valuehttp://hl7.org/fhir/StructureDefinition/alternate-canonical
    6. Extension.value[x]
    Definition

    Value of extension - must be one of a constrained set of the data types (see Extensibility for a list).

    ShortValue of extension
    Control10..1
    This element is affected by the following invariants: ext-1
    Typecanonical(CanonicalResource), date, Meta, Address, Attachment, integer, Count, DataRequirement, Dosage, uuid, Identifier, RatioRange, Coding, SampledData, id, positiveInt, Distance, Availability, integer64, Period, Duration, 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] NoteSeeChoice of Data Typesfor further information about how to use [x]
    Is Modifierfalse
    Primitive ValueThis primitive element may be present, or absent, or replaced by an extension
    Summaryfalse
    Invariantsele-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

    icon Changed:

    Used with inter-version extensions where the element being referenced by inter-version extension is of type 'canonical' and includes a reference to a resource whose canonical URL is different in the referencing version than it is in the FHIR version where the element was defined. E.g. if an R5 implementation were using inter-version extensions to support an element that referenced Bar, when in R7, the url would have been .../Foo. In this situation, the canonical element would have no value and would instead have an extension that referred to the canonical URL of the '../Bar' resource (which would technically not be supported in R7, but is appropriate in R5).

    ShortAlternative reference (target type is wrong)
    Control0..1
    Is Modifierfalse
    Invariantsele-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.

    ShortUnique id for inter-element referencing
    Control0..1
    This element is affected by the following invariants: ele-1
    Typeid
    Is Modifierfalse
    XML FormatIn the XML format, this property is represented as an attribute.
    Summaryfalse
    4. Extension.extension
    Definition

    An Extension

    ShortExtension
    Control0..0
    TypeExtension
    Is Modifierfalse
    Summaryfalse
    Invariantsele-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())
    SlicingThis 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.url
      Definition

      Source of the definition for the extension code - a logical name or a URL.

      Shortidentifies 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.

      Control1..1
      Typeuri
      Is Modifierfalse
      XML FormatIn the XML format, this property is represented as an attribute.
      Summaryfalse
      Fixed Valuehttp://hl7.org/fhir/StructureDefinition/alternate-canonical
      8. Extension.value[x]
      Definition

      icon Changed:

      Value of extension - must be one of a constrained set of the data types (see Extensibility for a list).

      ShortValue of extension
      Control1..1
      This element is affected by the following invariants: ext-1
      Typecanonical(CanonicalResource)
      [x] NoteSeeChoice of Data Typesfor further information about how to use [x]
      Is Modifierfalse
      Primitive ValueThis primitive element may be present, or absent, or replaced by an extension
      Summaryfalse
      Invariantsele-1: All FHIR elements must have a @value or children (hasValue() or (children().count() > id.count()))