FHIR R6 Patient Care Incubator
0.1.0 - ci-build International flag

FHIR R6 Patient Care Incubator, published by HL7 International / Patient Care. This guide is not an authorized publication; it is the continuous build for version 0.1.0 built by the FHIR (HL7® FHIR® Standard) CI Build. This version is based on the current content of https://github.com/HL7/pc-incubator/ and changes regularly. See the Directory of published versions

Resource Profile: Linkage - Detailed Descriptions

Page standards status: Draft Maturity Level: 0

Definitions for the Linkage resource profile.

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

0. Linkage
Definition

Identifies two or more records (resource instances) that refer to the same real-world "occurrence".


A resource that includes narrative, extensions, and contained resources.

ShortLinks records for 'same' itemA resource with narrative, extensions, and contained resources
Control0..*
Is Modifierfalse
Must Supportfalse
Summaryfalse
Invariantsdom-2: If the resource is contained in another resource, it SHALL NOT contain nested Resources (contained.contained.empty())
dom-3: If the resource is contained in another resource, it SHALL be referred to from elsewhere in the resource or SHALL refer to the containing resource (contained.where((('#'+id.trace('id') in %resource.descendants().select(reference | as(uri))) or descendants().where(reference='#' | as(uri)='#').exists()).not()).trace('unmatched', id).empty())
dom-4: If a resource is contained in another resource, it SHALL NOT have a meta.versionId or a meta.lastUpdated (contained.meta.versionId.empty() and contained.meta.lastUpdated.empty())
dom-5: If a resource is contained in another resource, it SHALL NOT have a security label (contained.meta.security.empty())
dom-6: A resource should have narrative for robust management (text.`div`.exists())
lnk-1: Must have at least two items (item.count()>1)
2. Linkage.id
Definition

The logical id of the resource, as used in the URL for the resource. Once assigned, this value never changes.

ShortLogical id of this artifact
Comments

Within the context of the FHIR RESTful interactions, the resource has an id except for cases like the create and conditional update. Otherwise, the use of the resouce id depends on the given use case.

Control0..1
Typeid
Is Modifierfalse
Must Supportfalse
Summarytrue
4. Linkage.meta
Definition

The metadata about the resource. This is content that is maintained by the infrastructure. Changes to the content might not always be associated with version changes to the resource.

ShortMetadata about the resource
Control0..1
TypeMeta
Is Modifierfalse
Must Supportfalse
Summarytrue
Invariantsele-1: All FHIR elements must have a @value or children (hasValue() or (children().count() > id.count()))
6. Linkage.implicitRules
Definition

A reference to a set of rules that were followed when the resource was constructed, and which must be understood when processing the content. Often, this is a reference to an implementation guide that defines the special rules along with other profiles etc.

ShortA set of rules under which this content was created
Comments

Asserting this rule set restricts the content to be only understood by a limited set of trading partners. This inherently limits the usefulness of the data in the long term. However, the existing health eco-system is highly fractured, and not yet ready to define, collect, and exchange data in a generally computable sense. Wherever possible, implementers and/or specification writers should avoid using this element. Often, when used, the URL is a reference to an implementation guide that defines these special rules as part of its narrative along with other profiles, value sets, etc.

Control0..1
Typeuri
Is Modifiertrue because This element is labeled as a modifier because the implicit rules may provide additional knowledge about the resource that modifies its meaning or interpretation
Primitive ValueThis primitive element may be present, or absent, or replaced by an extension
Must Supportfalse
Summarytrue
Invariantsele-1: All FHIR elements must have a @value or children (hasValue() or (children().count() > id.count()))
8. Linkage.language
Definition

The base language in which the resource is written.

ShortLanguage of the resource content
Comments

Language is provided to support indexing and accessibility (typically, services such as text to speech use the language tag). The html language tag in the narrative applies to the narrative. The language tag on the resource may be used to specify the language of other presentations generated from the data in the resource. Not all the content has to be in the base language. The Resource.language should not be assumed to apply to the narrative automatically. If a language is specified, it should it also be specified on the div element in the html (see rules in HTML5 for information about the relationship between xml:lang and the html lang attribute).

Control0..1
BindingThe codes SHALL be taken from AllLanguageshttp://hl7.org/fhir/ValueSet/all-languages|6.0.0-ballot3
(required to http://hl7.org/fhir/ValueSet/all-languages|6.0.0-ballot3)

IETF language tag for a human language

Typecode
Is Modifierfalse
Primitive ValueThis primitive element may be present, or absent, or replaced by an extension
Must Supportfalse
Summaryfalse
Invariantsele-1: All FHIR elements must have a @value or children (hasValue() or (children().count() > id.count()))
10. Linkage.text
Definition

A human-readable narrative that contains a summary of the resource and can be used to represent the content of the resource to a human. The narrative need not encode all the structured data, but is required to contain sufficient detail to make it "clinically safe" for a human to just read the narrative. Resource definitions may define what content should be represented in the narrative to ensure clinical safety.

ShortText summary of the resource, for human interpretation
Comments

Contained resources do not have a narrative. Resources that are not contained SHOULD have a narrative. In some cases, a resource may only have text with little or no additional discrete data (as long as all minOccurs=1 elements are satisfied). This may be necessary for data from legacy systems where information is captured as a "text blob" or where text is additionally entered raw or narrated and encoded information is added later.

Control0..1
This element is affected by the following invariants: dom-6
TypeNarrative
Is Modifierfalse
Must Supportfalse
Summaryfalse
Alternate Namesnarrative, html, xhtml, display
Invariantsele-1: All FHIR elements must have a @value or children (hasValue() or (children().count() > id.count()))
12. Linkage.contained
Definition

These resources do not have an independent existence apart from the resource that contains them - they cannot be identified independently, nor can they have their own independent transaction scope. This is allowed to be a Parameters resource if and only if it is referenced by a resource that provides context/meaning.

ShortContained, inline Resources
Comments

This should never be done when the content can be identified properly, as once identification is lost, it is extremely difficult (and context dependent) to restore it again. Contained resources may have profiles and tags in their meta elements, but SHALL NOT have security labels. Contained resources may be a resource type defined in the FHIR specification, or an additional resource.

Control0..*
This element is affected by the following invariants: dom-2, dom-4, dom-3, dom-5
TypeResource
Is Modifierfalse
Must Supportfalse
Summaryfalse
Alternate Namesinline resources, anonymous resources, contained resources
14. Linkage.extension
Definition

May be used to represent additional information that is not part of the basic definition of the resource. 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.

Control0..*
TypeExtension
Is Modifierfalse
Must Supportfalse
Summaryfalse
Alternate Namesextensions, user content
Invariantsele-1: All FHIR elements must have a @value or children (hasValue() or (children().count() > id.count()))
SlicingThis element introduces a set of slices on Linkage.extension. The slices areUnordered and Open, and can be differentiated using the following discriminators:
  • value @ url
  • 16. Linkage.modifierExtension
    Definition

    May be used to represent additional information that is not part of the basic definition of the resource and that modifies the understanding of the element that contains it and/or the understanding of the containing element's descendants. Usually modifier elements provide negation or qualification. 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 is allowed to define an extension, there is a set of requirements that SHALL be met as part of the definition of the extension. Applications processing a resource are required to check for modifier extensions.

    Modifier extensions SHALL NOT change the meaning of any elements on Resource or DomainResource (including cannot change the meaning of modifierExtension itself).

    ShortExtensions that cannot be ignored
    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..*
    TypeExtension
    Is Modifiertrue because Modifier extensions are expected to modify the meaning or interpretation of the resource that contains them
    Must Supportfalse
    Summarytrue
    Requirements

    Modifier extensions allow for extensions that cannot be safely ignored to be clearly distinguished from the vast majority of extensions which can be safely ignored. This promotes interoperability by eliminating the need for implementers to prohibit the presence of extensions. For further information, see the definition of modifier extensions.

    Alternate Namesextensions, user content
    Invariantsele-1: All FHIR elements must have a @value or children (hasValue() or (children().count() > id.count()))
    SlicingThis element introduces a set of slices on Linkage.modifierExtension. The slices areUnordered and Open, and can be differentiated using the following discriminators:
    • value @ url
    • 18. Linkage.active
      Definition

      Indicates whether the asserted set of linkages are considered to be "in effect".

      ShortWhether this linkage assertion is active or not
      Comments

      If false, any asserted linkages should not be considered current/relevant/applicable.

      Control0..1
      Typeboolean
      Primitive ValueThis primitive element may be present, or absent, or replaced by an extension
      Summarytrue
      Requirements

      Need to be able to mark a linkage record as not to be used because it was created in error.

      Meaning if MissingThis resource is generally assumed to be active if no value is provided for the active element
      20. Linkage.author
      Definition

      Identifies the user or organization responsible for asserting the linkages and establishing the context in which the nature of each linkage is evaluated.

      ShortWho is responsible for linkages
      Control0..1
      TypeReference(Practitioner, PractitionerRole, Organization)
      Summarytrue
      22. Linkage.item
      Definition

      Identifies a member of a set of resource instances considered to refer to the same real-world entity and classifies the role of the resource instance in the set.

      ShortItem to be linked
      Control1..*
      This element is affected by the following invariants: lnk-1
      TypeBackboneElement
      Summarytrue
      Invariantsele-1: All FHIR elements must have a @value or children or both (hasValue() or (children().count() > id.count()))
      24. Linkage.item.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
      Typeidstring
      Is Modifierfalse
      XML FormatIn the XML format, this property is represented as an attribute.
      Summaryfalse
      26. Linkage.item.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.

      Control0..*
      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()))
      SlicingThis element introduces a set of slices on Linkage.item.extension. The slices areUnordered and Open, and can be differentiated using the following discriminators:
      • value @ url
      • 28. Linkage.item.modifierExtension
        Definition

        May be used to represent additional information that is not part of the basic definition of the element and that modifies the understanding of the element in which it is contained and/or the understanding of the containing element's descendants. Usually modifier elements provide negation or qualification. 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. Applications processing a resource are required to check for modifier extensions.

        Modifier extensions SHALL NOT change the meaning of any elements on Resource or DomainResource (including cannot change the meaning of modifierExtension itself).

        ShortExtensions that cannot be ignored even if unrecognized
        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..*
        TypeExtension
        Is Modifiertrue because Modifier extensions are expected to modify the meaning or interpretation of the element that contains them
        Summarytrue
        Requirements

        Modifier extensions allow for extensions that cannot be safely ignored to be clearly distinguished from the vast majority of extensions which can be safely ignored. This promotes interoperability by eliminating the need for implementers to prohibit the presence of extensions. For further information, see the definition of modifier extensions.

        Alternate Namesextensions, user content, modifiers
        Invariantsele-1: All FHIR elements must have a @value or children (hasValue() or (children().count() > id.count()))
        30. Linkage.item.type
        Definition

        Distinguishes which item is "source of truth" (if any) and which items are no longer considered to be current representations.

        Shortsource | alternate | historical
        Control1..1
        BindingThe codes SHALL be taken from LinkageTypehttp://hl7.org/fhir/ValueSet/linkage-type
        (required to http://hl7.org/fhir/ValueSet/linkage-type)

        Used to distinguish different roles a resource can play within a set of linked resources.

        Typecode
        Primitive ValueThis primitive element may be present, or absent, or replaced by an extension
        Summarytrue
        32. Linkage.item.resource
        Definition

        The resource instance being linked as part of the group.

        ShortResource being linked
        Control1..1
        TypeReference(Resource)
        Summarytrue

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

        0. Linkage
        Definition

        Identifies two or more records (resource instances) that refer to the same real-world "occurrence".

        ShortLinks records for 'same' item
        Control0..*
        Invariantslnk-1: Must have at least two items (item.count()>1)
        2. Linkage.active
        Definition

        Indicates whether the asserted set of linkages are considered to be "in effect".

        ShortWhether this linkage assertion is active or not
        Comments

        If false, any asserted linkages should not be considered current/relevant/applicable.

        Control0..1
        Typeboolean
        Primitive ValueThis primitive element may be present, or absent, or replaced by an extension
        Requirements

        Need to be able to mark a linkage record as not to be used because it was created in error.

        Meaning if MissingThis resource is generally assumed to be active if no value is provided for the active element
        4. Linkage.author
        Definition

        Identifies the user or organization responsible for asserting the linkages and establishing the context in which the nature of each linkage is evaluated.

        ShortWho is responsible for linkages
        Control0..1
        TypeReference(Practitioner, PractitionerRole, Organization)
        6. Linkage.item
        Definition

        Identifies a member of a set of resource instances considered to refer to the same real-world entity and classifies the role of the resource instance in the set.

        ShortItem to be linked
        Control1..*
        This element is affected by the following invariants: lnk-1
        TypeBackboneElement
        8. Linkage.item.type
        Definition

        Distinguishes which item is "source of truth" (if any) and which items are no longer considered to be current representations.

        Shortsource | alternate | historical
        Control1..1
        BindingThe codes SHALL be taken from LinkageType
        (required to http://hl7.org/fhir/ValueSet/linkage-type)

        Used to distinguish different roles a resource can play within a set of linked resources.

        Typecode
        Primitive ValueThis primitive element may be present, or absent, or replaced by an extension
        10. Linkage.item.resource
        Definition

        The resource instance being linked as part of the group.

        ShortResource being linked
        Control1..1
        TypeReference(Resource)

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

        0. Linkage
        Definition

        Identifies two or more records (resource instances) that refer to the same real-world "occurrence".

        ShortLinks records for 'same' item
        Control0..*
        Is Modifierfalse
        Must Supportfalse
        Summaryfalse
        Invariantsdom-2: If the resource is contained in another resource, it SHALL NOT contain nested Resources (contained.contained.empty())
        dom-3: If the resource is contained in another resource, it SHALL be referred to from elsewhere in the resource or SHALL refer to the containing resource (contained.where((('#'+id.trace('id') in %resource.descendants().select(reference | as(uri))) or descendants().where(reference='#' | as(uri)='#').exists()).not()).trace('unmatched', id).empty())
        dom-4: If a resource is contained in another resource, it SHALL NOT have a meta.versionId or a meta.lastUpdated (contained.meta.versionId.empty() and contained.meta.lastUpdated.empty())
        dom-5: If a resource is contained in another resource, it SHALL NOT have a security label (contained.meta.security.empty())
        dom-6: A resource should have narrative for robust management (text.`div`.exists())
        lnk-1: Must have at least two items (item.count()>1)
        2. Linkage.id
        Definition

        The logical id of the resource, as used in the URL for the resource. Once assigned, this value never changes.

        ShortLogical id of this artifact
        Comments

        Within the context of the FHIR RESTful interactions, the resource has an id except for cases like the create and conditional update. Otherwise, the use of the resouce id depends on the given use case.

        Control0..1
        Typeid
        Is Modifierfalse
        Must Supportfalse
        Summarytrue
        4. Linkage.meta
        Definition

        The metadata about the resource. This is content that is maintained by the infrastructure. Changes to the content might not always be associated with version changes to the resource.

        ShortMetadata about the resource
        Control0..1
        TypeMeta
        Is Modifierfalse
        Must Supportfalse
        Summarytrue
        Invariantsele-1: All FHIR elements must have a @value or children (hasValue() or (children().count() > id.count()))
        6. Linkage.implicitRules
        Definition

        A reference to a set of rules that were followed when the resource was constructed, and which must be understood when processing the content. Often, this is a reference to an implementation guide that defines the special rules along with other profiles etc.

        ShortA set of rules under which this content was created
        Comments

        Asserting this rule set restricts the content to be only understood by a limited set of trading partners. This inherently limits the usefulness of the data in the long term. However, the existing health eco-system is highly fractured, and not yet ready to define, collect, and exchange data in a generally computable sense. Wherever possible, implementers and/or specification writers should avoid using this element. Often, when used, the URL is a reference to an implementation guide that defines these special rules as part of its narrative along with other profiles, value sets, etc.

        Control0..1
        Typeuri
        Is Modifiertrue because This element is labeled as a modifier because the implicit rules may provide additional knowledge about the resource that modifies its meaning or interpretation
        Primitive ValueThis primitive element may be present, or absent, or replaced by an extension
        Must Supportfalse
        Summarytrue
        Invariantsele-1: All FHIR elements must have a @value or children (hasValue() or (children().count() > id.count()))
        8. Linkage.language
        Definition

        The base language in which the resource is written.

        ShortLanguage of the resource content
        Comments

        Language is provided to support indexing and accessibility (typically, services such as text to speech use the language tag). The html language tag in the narrative applies to the narrative. The language tag on the resource may be used to specify the language of other presentations generated from the data in the resource. Not all the content has to be in the base language. The Resource.language should not be assumed to apply to the narrative automatically. If a language is specified, it should it also be specified on the div element in the html (see rules in HTML5 for information about the relationship between xml:lang and the html lang attribute).

        Control0..1
        BindingThe codes SHALL be taken from AllLanguages
        (required to http://hl7.org/fhir/ValueSet/all-languages|6.0.0-ballot3)

        IETF language tag for a human language

        Typecode
        Is Modifierfalse
        Primitive ValueThis primitive element may be present, or absent, or replaced by an extension
        Must Supportfalse
        Summaryfalse
        Invariantsele-1: All FHIR elements must have a @value or children (hasValue() or (children().count() > id.count()))
        10. Linkage.text
        Definition

        A human-readable narrative that contains a summary of the resource and can be used to represent the content of the resource to a human. The narrative need not encode all the structured data, but is required to contain sufficient detail to make it "clinically safe" for a human to just read the narrative. Resource definitions may define what content should be represented in the narrative to ensure clinical safety.

        ShortText summary of the resource, for human interpretation
        Comments

        Contained resources do not have a narrative. Resources that are not contained SHOULD have a narrative. In some cases, a resource may only have text with little or no additional discrete data (as long as all minOccurs=1 elements are satisfied). This may be necessary for data from legacy systems where information is captured as a "text blob" or where text is additionally entered raw or narrated and encoded information is added later.

        Control0..1
        This element is affected by the following invariants: dom-6
        TypeNarrative
        Is Modifierfalse
        Must Supportfalse
        Summaryfalse
        Alternate Namesnarrative, html, xhtml, display
        Invariantsele-1: All FHIR elements must have a @value or children (hasValue() or (children().count() > id.count()))
        12. Linkage.contained
        Definition

        These resources do not have an independent existence apart from the resource that contains them - they cannot be identified independently, nor can they have their own independent transaction scope. This is allowed to be a Parameters resource if and only if it is referenced by a resource that provides context/meaning.

        ShortContained, inline Resources
        Comments

        This should never be done when the content can be identified properly, as once identification is lost, it is extremely difficult (and context dependent) to restore it again. Contained resources may have profiles and tags in their meta elements, but SHALL NOT have security labels. Contained resources may be a resource type defined in the FHIR specification, or an additional resource.

        Control0..*
        This element is affected by the following invariants: dom-2, dom-4, dom-3, dom-5
        TypeResource
        Is Modifierfalse
        Must Supportfalse
        Summaryfalse
        Alternate Namesinline resources, anonymous resources, contained resources
        14. Linkage.extension
        Definition

        May be used to represent additional information that is not part of the basic definition of the resource. 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.

        Control0..*
        TypeExtension
        Is Modifierfalse
        Must Supportfalse
        Summaryfalse
        Alternate Namesextensions, user content
        Invariantsele-1: All FHIR elements must have a @value or children (hasValue() or (children().count() > id.count()))
        SlicingThis element introduces a set of slices on Linkage.extension. The slices areUnordered and Open, and can be differentiated using the following discriminators:
        • value @ url
        • 16. Linkage.modifierExtension
          Definition

          May be used to represent additional information that is not part of the basic definition of the resource and that modifies the understanding of the element that contains it and/or the understanding of the containing element's descendants. Usually modifier elements provide negation or qualification. 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 is allowed to define an extension, there is a set of requirements that SHALL be met as part of the definition of the extension. Applications processing a resource are required to check for modifier extensions.

          Modifier extensions SHALL NOT change the meaning of any elements on Resource or DomainResource (including cannot change the meaning of modifierExtension itself).

          ShortExtensions that cannot be ignored
          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..*
          TypeExtension
          Is Modifiertrue because Modifier extensions are expected to modify the meaning or interpretation of the resource that contains them
          Must Supportfalse
          Summarytrue
          Requirements

          Modifier extensions allow for extensions that cannot be safely ignored to be clearly distinguished from the vast majority of extensions which can be safely ignored. This promotes interoperability by eliminating the need for implementers to prohibit the presence of extensions. For further information, see the definition of modifier extensions.

          Alternate Namesextensions, user content
          Invariantsele-1: All FHIR elements must have a @value or children (hasValue() or (children().count() > id.count()))
          SlicingThis element introduces a set of slices on Linkage.modifierExtension. The slices areUnordered and Open, and can be differentiated using the following discriminators:
          • value @ url
          • 18. Linkage.active
            Definition

            Indicates whether the asserted set of linkages are considered to be "in effect".

            ShortWhether this linkage assertion is active or not
            Comments

            If false, any asserted linkages should not be considered current/relevant/applicable.

            Control0..1
            Typeboolean
            Primitive ValueThis primitive element may be present, or absent, or replaced by an extension
            Summarytrue
            Requirements

            Need to be able to mark a linkage record as not to be used because it was created in error.

            Meaning if MissingThis resource is generally assumed to be active if no value is provided for the active element
            20. Linkage.author
            Definition

            Identifies the user or organization responsible for asserting the linkages and establishing the context in which the nature of each linkage is evaluated.

            ShortWho is responsible for linkages
            Control0..1
            TypeReference(Practitioner, PractitionerRole, Organization)
            Summarytrue
            22. Linkage.item
            Definition

            Identifies a member of a set of resource instances considered to refer to the same real-world entity and classifies the role of the resource instance in the set.

            ShortItem to be linked
            Control1..*
            This element is affected by the following invariants: lnk-1
            TypeBackboneElement
            Summarytrue
            Invariantsele-1: All FHIR elements must have a @value or children or both (hasValue() or (children().count() > id.count()))
            24. Linkage.item.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
            26. Linkage.item.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.

            Control0..*
            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()))
            SlicingThis element introduces a set of slices on Linkage.item.extension. The slices areUnordered and Open, and can be differentiated using the following discriminators:
            • value @ url
            • 28. Linkage.item.modifierExtension
              Definition

              May be used to represent additional information that is not part of the basic definition of the element and that modifies the understanding of the element in which it is contained and/or the understanding of the containing element's descendants. Usually modifier elements provide negation or qualification. 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. Applications processing a resource are required to check for modifier extensions.

              Modifier extensions SHALL NOT change the meaning of any elements on Resource or DomainResource (including cannot change the meaning of modifierExtension itself).

              ShortExtensions that cannot be ignored even if unrecognized
              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..*
              TypeExtension
              Is Modifiertrue because Modifier extensions are expected to modify the meaning or interpretation of the element that contains them
              Summarytrue
              Requirements

              Modifier extensions allow for extensions that cannot be safely ignored to be clearly distinguished from the vast majority of extensions which can be safely ignored. This promotes interoperability by eliminating the need for implementers to prohibit the presence of extensions. For further information, see the definition of modifier extensions.

              Alternate Namesextensions, user content, modifiers
              Invariantsele-1: All FHIR elements must have a @value or children (hasValue() or (children().count() > id.count()))
              30. Linkage.item.type
              Definition

              Distinguishes which item is "source of truth" (if any) and which items are no longer considered to be current representations.

              Shortsource | alternate | historical
              Control1..1
              BindingThe codes SHALL be taken from LinkageType
              (required to http://hl7.org/fhir/ValueSet/linkage-type)

              Used to distinguish different roles a resource can play within a set of linked resources.

              Typecode
              Primitive ValueThis primitive element may be present, or absent, or replaced by an extension
              Summarytrue
              32. Linkage.item.resource
              Definition

              The resource instance being linked as part of the group.

              ShortResource being linked
              Control1..1
              TypeReference(Resource)
              Summarytrue