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: IGSourceFile - Detailed Descriptions

Page standards status: Trial-use Maturity Level: 2

Definitions for the implementationguide-sourceFile extension.

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

0. Extension
Definition

Identifies files used as part of the the publication process other than resources referenced in definition.resource.

ShortAdditional files used in publication
Comments

When 'exporting' the referenced file for use in publication, if storing the content as a resource, the exported syntax (XML, JSON, or RDF) should be driven by the file extension of the specified location.

Control0..*
2. Extension.extension:file
Slice Namefile
Definition

The location of the file on a server used by the IG publication process

ShortLocation on server
Comments

This will often be a DocumentReference or Media resource (depending on FHIR version) containing the relevant content.

Control1..1
4. Extension.extension:file.extension
Control0..0
6. Extension.extension:file.url
Fixed Valuefile
8. Extension.extension:file.value[x]
Control1..?
TypeReference
[x] NoteSeeChoice of Data Typesfor further information about how to use [x]
10. Extension.extension:location
Slice Namelocation
Definition

The relative path (with respect to the IG base folder) and name of the file as it should be positioned prior to processing by the IG publisher

ShortPath for publisher
Control1..1
12. Extension.extension:location.extension
Control0..0
14. Extension.extension:location.url
Fixed Valuefile
16. Extension.extension:location.value[x]
Control1..?
Typestring
[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
18. Extension.extension:keepAsResource
Slice NamekeepAsResource
Definition

The default behavior if the Reference is to a Media or DocumentReference is for the 'attachment' to be what is persisted in the 'location'. If this flag is set to true, then the referenced resource will be persisted 'as is' - I.e. a Media or DocumentReference.

ShortUse attachment or resource?
Control0..1
20. Extension.extension:keepAsResource.extension
Control0..0
22. Extension.extension:keepAsResource.url
Fixed Valuefile
24. Extension.extension:keepAsResource.value[x]
Control1..?
Typeboolean
[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
26. Extension.url
Fixed Valuehttp://hl7.org/fhir/StructureDefinition/implementationguide-sourceFile
28. Extension.value[x]
Control0..0

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

0. Extension
Definition

Identifies files used as part of the the publication process other than resources referenced in definition.resource.


Optional Extension Element - found in all resources.

ShortAdditional files used in publicationOptional Extensions Element
Comments

When 'exporting' the referenced file for use in publication, if storing the content as a resource, the exported syntax (XML, JSON, or RDF) should be driven by the file extension of the specified location.

Control0..*
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

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.

ShortAdditional 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.

Controlicon Changed:20..*
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.extension:file
    Slice Namefile
    Definition

    The location of the file on a server used by the IG publication process

    ShortLocation on serverAdditional content defined by implementations
    Comments

    This will often be a DocumentReference or Media resource (depending on FHIR version) containing the relevant content.

    Control10..1*
    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())
    6. Extension.extension:file.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.extension. The slices areUnordered and Open, and can be differentiated using the following discriminators:
    • value @ url
    • 8. Extension.extension:file.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 Valuefile
      10. Extension.extension:file.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
      TypeReference, 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] NoteSeeChoice of Data Typesfor further information about how to use [x]
      Is Modifierfalse
      Summaryfalse
      Invariantsele-1: All FHIR elements must have a @value or children (hasValue() or (children().count() > id.count()))
      12. Extension.extension:location
      Slice Namelocation
      Definition

      The relative path (with respect to the IG base folder) and name of the file as it should be positioned prior to processing by the IG publisher

      ShortPath for publisherAdditional content defined by implementations
      Control10..1*
      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())
      14. Extension.extension:location.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.extension. The slices areUnordered and Open, and can be differentiated using the following discriminators:
      • value @ url
      • 16. Extension.extension:location.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 Valuefile
        18. Extension.extension:location.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
        Typestring, 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] 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()))
        20. Extension.extension:keepAsResource
        Slice NamekeepAsResource
        Definition

        The default behavior if the Reference is to a Media or DocumentReference is for the 'attachment' to be what is persisted in the 'location'. If this flag is set to true, then the referenced resource will be persisted 'as is' - I.e. a Media or DocumentReference.

        ShortUse attachment or resource?Additional content defined by implementations
        Control0..1*
        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())
        22. Extension.extension:keepAsResource.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.extension. The slices areUnordered and Open, and can be differentiated using the following discriminators:
        • value @ url
        • 24. Extension.extension:keepAsResource.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 Valuefile
          26. Extension.extension:keepAsResource.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
          Typeboolean, 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, Reference, TriggerDefinition, Quantity, uri, url, Annotation, ContactDetail, 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()))
          28. 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/implementationguide-sourceFile
          30. 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
          Control0..01
          This element is affected by the following invariants: ext-1
          TypeChoice 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 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

          Identifies files used as part of the the publication process other than resources referenced in definition.resource.

          ShortAdditional files used in publication
          Comments

          When 'exporting' the referenced file for use in publication, if storing the content as a resource, the exported syntax (XML, JSON, or RDF) should be driven by the file extension of the specified location.

          Control0..*
          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

          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.

          ShortAdditional 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.

          Controlicon Changed:2..*
          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
          • 6. Extension.extension:file
            Slice Namefile
            Definition

            The location of the file on a server used by the IG publication process

            ShortLocation on server
            Comments

            This will often be a DocumentReference or Media resource (depending on FHIR version) containing the relevant content.

            Control1..1
            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())
            8. Extension.extension:file.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
            10. Extension.extension:file.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.extension. The slices areUnordered and Open, and can be differentiated using the following discriminators:
            • value @ url
            • 12. Extension.extension:file.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 Valuefile
              14. Extension.extension:file.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
              Control1..1
              This element is affected by the following invariants: ext-1
              TypeReference
              [x] NoteSeeChoice of Data Typesfor further information about how to use [x]
              Is Modifierfalse
              Summaryfalse
              Invariantsele-1: All FHIR elements must have a @value or children (hasValue() or (children().count() > id.count()))
              16. Extension.extension:location
              Slice Namelocation
              Definition

              The relative path (with respect to the IG base folder) and name of the file as it should be positioned prior to processing by the IG publisher

              ShortPath for publisher
              Control1..1
              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())
              18. Extension.extension:location.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
              20. Extension.extension:location.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.extension. The slices areUnordered and Open, and can be differentiated using the following discriminators:
              • value @ url
              • 22. Extension.extension:location.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 Valuefile
                24. Extension.extension:location.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
                Control1..1
                This element is affected by the following invariants: ext-1
                Typestring
                [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()))
                26. Extension.extension:keepAsResource
                Slice NamekeepAsResource
                Definition

                The default behavior if the Reference is to a Media or DocumentReference is for the 'attachment' to be what is persisted in the 'location'. If this flag is set to true, then the referenced resource will be persisted 'as is' - I.e. a Media or DocumentReference.

                ShortUse attachment or resource?
                Control0..1
                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())
                28. Extension.extension:keepAsResource.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
                30. Extension.extension:keepAsResource.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.extension. The slices areUnordered and Open, and can be differentiated using the following discriminators:
                • value @ url
                • 32. Extension.extension:keepAsResource.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 Valuefile
                  34. Extension.extension:keepAsResource.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
                  Control1..1
                  This element is affected by the following invariants: ext-1
                  Typeboolean
                  [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()))
                  36. 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/implementationguide-sourceFile
                  38. 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
                  Control0..0
                  This element is affected by the following invariants: ext-1
                  TypeChoice 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 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()))