Structured Data Capture
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Structured Data Capture, published by HL7 International / FHIR Infrastructure. This guide is not an authorized publication; it is the continuous build for version 4.0.0-ballot built by the FHIR (HL7® FHIR® Standard) CI Build. This version is based on the current content of https://github.com/HL7/sdc/ and changes regularly. See the Directory of published versions

Resource Profile: SDCCodeSystem - Detailed Descriptions

Page standards status: Trial-use Maturity Level: 4

Definitions for the sdc-codesystem resource profile.

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

0. CodeSystem
Definition

Sets expectations for SDC-conformant systems around value set support for representing permitted question answers.


The CodeSystem resource is used to declare the existence of and describe a code system or code system supplement and its key properties, and optionally define a part or all of its content.

ShortDeclares the existence of and describes a code system or code system supplement
Control0..*
Is Modifierfalse
Summaryfalse
Invariantscsd-0: Name should be usable as an identifier for the module by machine processing applications such as code generation (name.matches('[A-Z]([A-Za-z0-9_]){0,254}'))
csd-1: Within a code system definition, all the codes SHALL be unique (concept.code.combine($this.descendants().concept.code).isDistinct())
dom-2: If the resource is contained in another resource, it SHALL NOT contain nested Resources (contained.contained.empty())
dom-3: If the resource is contained in another resource, it SHALL be referred to from elsewhere in the resource or SHALL refer to the containing resource (contained.where((('#'+id in (%resource.descendants().reference | %resource.descendants().as(canonical) | %resource.descendants().as(uri) | %resource.descendants().as(url))) or descendants().where(reference = '#').exists() or descendants().where(as(canonical) = '#').exists() or descendants().where(as(canonical) = '#').exists()).not()).trace('unmatched', id).empty())
dom-4: If a resource is contained in another resource, it SHALL NOT have a meta.versionId or a meta.lastUpdated (contained.meta.versionId.empty() and contained.meta.lastUpdated.empty())
dom-5: If a resource is contained in another resource, it SHALL NOT have a security label (contained.meta.security.empty())
dom-6: A resource should have narrative for robust management (text.`div`.exists())
csd-0: Name should be usable as an identifier for the module by machine processing applications such as code generation (name.matches('[A-Z]([A-Za-z0-9_]){0,254}'))
csd-1: Within a code system definition, all the codes SHALL be unique (concept.code.combine($this.descendants().concept.code).isDistinct())
2. CodeSystem.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 it's 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 it's meaning or interpretation
Primitive ValueThis primitive element may be present, or absent, or replaced by an extension
Summarytrue
Invariantsele-1: All FHIR elements must have a @value or children (hasValue() or (children().count() > id.count()))
4. CodeSystem.modifierExtension
Definition

An Extension


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 manageable, 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).

ShortExtensionExtensions 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
Summaryfalse
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()))
ext-1: Must have either extensions or value[x], not both (extension.exists() != value.exists())
SlicingThis element introduces a set of slices on CodeSystem.modifierExtension. The slices areUnordered and Open, and can be differentiated using the following discriminators:
  • value @ url
  • 6. CodeSystem.modifierExtension:rendering-criticalExtension
    Slice Namerendering-criticalExtension
    Definition

    Indicates an extension that must be supported by the system presenting the instance for data capture or end-user consumption. If a system does not recognize the extension or cannot implement the functionality defined by the extension, it should display an error message or warning and refrain from presenting the instance to the user or using it when capturing data.

    ShortExtension that must be supported
    Comments

    This may point to extensions that control the appearance of data elements, control what value elements have, what elements are or are not available, what elements can or cannot be edited, or rules about how editing may occur. This extension does NOT apply when simply rendering a resource for publication purposes or for other purposes not intended for end-user data capture or data consumption.

    Control0..*
    This element is affected by the following invariants: ele-1
    TypeExtension(Rendering Critical Extension) (Extension Type: canonical)
    Is Modifiertrue because Indicates that the Questionnaire can't be safely rendered in certain situations
    Must Supporttrue
    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())
    ext-1: Must have either extensions or value[x], not both (extension.exists() != value.exists())
    8. CodeSystem.url
    Definition

    An absolute URI that is used to identify this code system when it is referenced in a specification, model, design or an instance; also called its canonical identifier. This SHOULD be globally unique and SHOULD be a literal address at which at which an authoritative instance of this code system is (or will be) published. This URL can be the target of a canonical reference. It SHALL remain the same when the code system is stored on different servers. This is used in Coding.system.

    ShortCanonical identifier for this code system, represented as a URI (globally unique) (Coding.system)
    Comments

    Can be a urn:uuid: or a urn:oid: but real http: addresses are preferred. Multiple instances may share the same URL if they have a distinct version.

    The determination of when to create a new version of a resource (same url, new version) vs. defining a new artifact is up to the author. Considerations for making this decision are found in Technical and Business Versions.

    In some cases, the resource can no longer be found at the stated url, but the url itself cannot change. Implementations can use the meta.source element to indicate where the current master source of the resource can be found.

    Control0..1
    Typeuri
    Is Modifierfalse
    Primitive ValueThis primitive element may be present, or absent, or replaced by an extension
    Must Supporttrue
    Summarytrue
    Requirements

    Allows the code system to be referenced by a single globally unique identifier.

    Invariantsele-1: All FHIR elements must have a @value or children (hasValue() or (children().count() > id.count()))
    10. CodeSystem.name
    Definition

    A natural language name identifying the code system. This name should be usable as an identifier for the module by machine processing applications such as code generation.

    ShortName for this code system (computer friendly)
    Comments

    The name is not expected to be globally unique. The name should be a simple alphanumeric type name to ensure that it is machine-processing friendly.

    Control0..1
    This element is affected by the following invariants: inv-0
    Typestring
    Is Modifierfalse
    Primitive ValueThis primitive element may be present, or absent, or replaced by an extension
    Summarytrue
    Requirements

    Support human navigation and code generation.

    Invariantsele-1: All FHIR elements must have a @value or children (hasValue() or (children().count() > id.count()))
    12. CodeSystem.status
    Definition

    The date (and optionally time) when the code system resource was created or revised.

    Shortdraft | active | retired | unknown
    Comments

    Allows filtering of code systems that are appropriate for use versus not.

    Control1..1
    BindingThe codes SHALL be taken from PublicationStatushttp://hl7.org/fhir/ValueSet/publication-status|4.0.1
    (required to http://hl7.org/fhir/ValueSet/publication-status|4.0.1)

    The lifecycle status of an artifact.

    Typecode
    Is Modifiertrue because This is labeled as "Is Modifier" because applications should not use a retired {{title}} without due consideration
    Primitive ValueThis primitive element may be present, or absent, or replaced by an extension
    Must Supporttrue
    Summarytrue
    Invariantsele-1: All FHIR elements must have a @value or children (hasValue() or (children().count() > id.count()))
    14. CodeSystem.experimental
    Definition

    A Boolean value to indicate that this code system is authored for testing purposes (or education/evaluation/marketing) and is not intended to be used for genuine usage.

    ShortFor testing purposes, not real usage
    Comments

    Allows filtering of code systems that are appropriate for use versus not.

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

    Enables experimental content to be developed following the same lifecycle that would be used for a production-level code system.

    Invariantsele-1: All FHIR elements must have a @value or children (hasValue() or (children().count() > id.count()))
    16. CodeSystem.date
    Definition

    The date (and optionally time) when the code system was published. The date must change when the business version changes and it must change if the status code changes. In addition, it should change when the substantive content of the code system changes.

    ShortDate last changed
    Comments

    Note that this is not the same as the resource last-modified-date, since the resource may be a secondary representation of the code system. Additional specific dates may be added as extensions or be found by consulting Provenances associated with past versions of the resource.

    Control0..1
    TypedateTime
    Is Modifierfalse
    Primitive ValueThis primitive element may be present, or absent, or replaced by an extension
    Must Supporttrue
    Summarytrue
    Alternate NamesRevision Date
    Invariantsele-1: All FHIR elements must have a @value or children (hasValue() or (children().count() > id.count()))
    18. CodeSystem.description
    Definition

    A free text natural language description of the code system from a consumer's perspective.

    ShortNatural language description of the code system
    Comments

    This description can be used to capture details such as why the code system was built, comments about misuse, instructions for clinical use and interpretation, literature references, examples from the paper world, etc. It is not a rendering of the code system as conveyed in the 'text' field of the resource itself. This item SHOULD be populated unless the information is available from context (e.g. the language of the code system is presumed to be the predominant language in the place the code system was created).

    Control0..1
    Typemarkdown
    Is Modifierfalse
    Primitive ValueThis primitive element may be present, or absent, or replaced by an extension
    Must Supporttrue
    Summaryfalse
    Alternate NamesScope, Purpose
    Invariantsele-1: All FHIR elements must have a @value or children (hasValue() or (children().count() > id.count()))
    20. CodeSystem.caseSensitive
    Definition

    If code comparison is case sensitive when codes within this system are compared to each other.

    ShortIf code comparison is case sensitive
    Comments

    If this value is missing, then it is not specified whether a code system is case sensitive or not. When the rule is not known, Postel's law should be followed: produce codes with the correct case, and accept codes in any case. This element is primarily provided to support validation software.

    Control10..1
    Typeboolean
    Is Modifierfalse
    Primitive ValueThis primitive element may be present, or absent, or replaced by an extension
    Must Supporttrue
    Summarytrue
    Invariantsele-1: All FHIR elements must have a @value or children (hasValue() or (children().count() > id.count()))
    22. CodeSystem.compositional
    Definition

    The code system defines a compositional (post-coordination) grammar.

    ShortIf code system defines a compositional grammar
    Comments

    Note that the code system resource does not define what the compositional grammar is, only whether or not there is one.

    Control0..01
    Typeboolean
    Is Modifierfalse
    Primitive ValueThis primitive element may be present, or absent, or replaced by an extension
    Summarytrue
    Alternate Namesgrammar
    Invariantsele-1: All FHIR elements must have a @value or children (hasValue() or (children().count() > id.count()))
    24. CodeSystem.versionNeeded
    Definition

    This flag is used to signify that the code system does not commit to concept permanence across versions. If true, a version must be specified when referencing this code system.

    ShortIf definitions are not stable
    Comments

    Best practice is that code systems do not redefine concepts, or that if concepts are redefined, a new code system definition is created. But this is not always possible, so some code systems may be defined as 'versionNeeded'.

    Most code systems occasionally refine the displays defined for concepts between versions. Contexts in which the concept display values are validated may require that the version be specified for some code systems irrespective of the value of this property.

    Control0..01
    Typeboolean
    Is Modifierfalse
    Primitive ValueThis primitive element may be present, or absent, or replaced by an extension
    Summarytrue
    Invariantsele-1: All FHIR elements must have a @value or children (hasValue() or (children().count() > id.count()))
    26. CodeSystem.content
    Definition

    The extent of the content of the code system (the concepts and codes it defines) are represented in this resource instance.

    Shortnot-present | example | fragment | complete | supplement
    Control1..1
    BindingThe codes SHALL be taken from CodeSystemContentModehttp://hl7.org/fhir/ValueSet/codesystem-content-mode|4.0.1
    (required to http://hl7.org/fhir/ValueSet/codesystem-content-mode|4.0.1)

    The extent of the content of the code system (the concepts and codes it defines) are represented in a code system resource.

    Typecode
    Is Modifierfalse
    Primitive ValueThis primitive element may be present, or absent, or replaced by an extension
    Must Supporttrue
    Summarytrue
    Invariantsele-1: All FHIR elements must have a @value or children (hasValue() or (children().count() > id.count()))
    28. CodeSystem.property
    Definition

    A property defines an additional slot through which additional information can be provided about a concept.

    ShortAdditional information supplied about each concept
    Control0..*
    TypeBackboneElement
    Is Modifierfalse
    Must Supporttrue
    Summarytrue
    Requirements

    Property is mustSupport because it is used to express weights as well as elements that may be relevant for rendering or performing logic on codes

    Invariantsele-1: All FHIR elements must have a @value or children (hasValue() or (children().count() > id.count()))
    30. CodeSystem.property.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 manageable, 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()))
    ext-1: Must have either extensions or value[x], not both (extension.exists() != value.exists())
    32. CodeSystem.property.code
    Definition

    A code that is used to identify the property. The code is used internally (in CodeSystem.concept.property.code) and also externally, such as in property filters.

    ShortIdentifies the property on the concepts, and when referred to in operations
    Control1..1
    Typecode
    Is Modifierfalse
    Primitive ValueThis primitive element may be present, or absent, or replaced by an extension
    Must Supporttrue
    Summarytrue
    Invariantsele-1: All FHIR elements must have a @value or children (hasValue() or (children().count() > id.count()))
    34. CodeSystem.property.uri
    Definition

    Reference to the formal meaning of the property. One possible source of meaning is the Concept Properties code system.


    Reference to the formal meaning of the property. One possible source of meaning is the Concept Properties code system.

    ShortFormal identifier for the property
    Control0..1
    Typeuri
    Is Modifierfalse
    Primitive ValueThis primitive element may be present, or absent, or replaced by an extension
    Must Supporttrue
    Summarytrue
    Invariantsele-1: All FHIR elements must have a @value or children (hasValue() or (children().count() > id.count()))
    36. CodeSystem.property.type
    Definition

    The type of the property value. Properties of type "code" contain a code defined by the code system (e.g. a reference to another defined concept).

    Shortcode | Coding | string | integer | boolean | dateTime | decimal
    Control1..1
    BindingThe codes SHALL be taken from PropertyTypehttp://hl7.org/fhir/ValueSet/concept-property-type|4.0.1
    (required to http://hl7.org/fhir/ValueSet/concept-property-type|4.0.1)

    The type of a property value.

    Typecode
    Is Modifierfalse
    Primitive ValueThis primitive element may be present, or absent, or replaced by an extension
    Must Supporttrue
    Summarytrue
    Invariantsele-1: All FHIR elements must have a @value or children (hasValue() or (children().count() > id.count()))
    38. CodeSystem.concept
    Definition

    Concepts that are in the code system. The concept definitions are inherently hierarchical, but the definitions must be consulted to determine what the meanings of the hierarchical relationships are.

    ShortConcepts in the code system
    Comments

    If this is empty, it means that the code system resource does not represent the content of the code system.

    Control0..*
    TypeBackboneElement
    Is Modifierfalse
    Must Supporttrue
    Summaryfalse
    Invariantsele-1: All FHIR elements must have a @value or children (hasValue() or (children().count() > id.count()))
    40. CodeSystem.concept.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 manageable, 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()))
    ext-1: Must have either extensions or value[x], not both (extension.exists() != value.exists())
    42. CodeSystem.concept.code
    Definition

    A code - a text symbol - that uniquely identifies the concept within the code system.

    ShortCode that identifies concept
    Control1..1
    Typecode
    Is Modifierfalse
    Primitive ValueThis primitive element may be present, or absent, or replaced by an extension
    Must Supporttrue
    Summaryfalse
    Invariantsele-1: All FHIR elements must have a @value or children (hasValue() or (children().count() > id.count()))
    44. CodeSystem.concept.display
    Definition

    A human readable string that is the recommended default way to present this concept to a user.

    ShortText to display to the user
    Control0..1
    Typestring
    Is Modifierfalse
    Primitive ValueThis primitive element may be present, or absent, or replaced by an extension
    Must Supporttrue
    Summaryfalse
    Invariantsele-1: All FHIR elements must have a @value or children (hasValue() or (children().count() > id.count()))
    46. CodeSystem.concept.display.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 manageable, 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..*
    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())
    ext-1: Must have either extensions or value[x], not both (extension.exists() != value.exists())
    SlicingThis element introduces a set of slices on CodeSystem.concept.display.extension. The slices areUnordered and Open, and can be differentiated using the following discriminators:
    • value @ url
    • 48. CodeSystem.concept.display.extension:conceptDisplayLabel-renderingStyle
      Slice NameconceptDisplayLabel-renderingStyle
      Definition

      Identifies how the specified element should be rendered when displayed.

      ShortHtml style value
      Comments

      This extension would be equivalent to setting the HTML "style" attribute on the root element for the element containing the extension.

      For questionnaires, see additional guidance and examples in the SDC implementation guide.

      Control0..1
      TypeExtension(Rendering Style) (Extension Type: string)
      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())
      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())
      50. CodeSystem.concept.display.extension:conceptDisplayLabel-xhtml
      Slice NameconceptDisplayLabel-xhtml
      Definition

      This is an equivalent of the string on which the extension is sent, but includes additional XHTML markup, such as bold, italics, styles, tables, etc. Existing restrictions on XHTML content apply. Note that using markdown allows for greater flexibility of display.

      ShortString equivalent with html markup
      Comments

      For questionnaires, see additional guidance and examples in the SDC implementation guide.

      Control0..1
      TypeExtension(XHTML Representation) (Extension Type: string)
      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())
      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())
      52. CodeSystem.concept.definition
      Definition

      The formal definition of the concept. The code system resource does not make formal definitions required, because of the prevalence of legacy systems. However, they are highly recommended, as without them there is no formal meaning associated with the concept.

      ShortFormal definition
      Control0..1
      Typestring
      Is Modifierfalse
      Primitive ValueThis primitive element may be present, or absent, or replaced by an extension
      Must Supporttrue
      Summaryfalse
      Invariantsele-1: All FHIR elements must have a @value or children (hasValue() or (children().count() > id.count()))
      54. CodeSystem.concept.property
      Definition

      A property value for this concept.

      ShortProperty value for the concept
      Control0..*
      TypeBackboneElement
      Is Modifierfalse
      Must Supporttrue
      Summaryfalse
      Requirements

      Property is mustSupport because it is used to express weights as well as elements that may be relevant for rendering or performing logic on codes

      Invariantsele-1: All FHIR elements must have a @value or children (hasValue() or (children().count() > id.count()))
      56. CodeSystem.concept.property.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 manageable, 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()))
      ext-1: Must have either extensions or value[x], not both (extension.exists() != value.exists())
      58. CodeSystem.concept.property.code
      Definition

      A code that is a reference to CodeSystem.property.code.

      ShortReference to CodeSystem.property.code
      Control1..1
      Typecode
      Is Modifierfalse
      Primitive ValueThis primitive element may be present, or absent, or replaced by an extension
      Must Supporttrue
      Summaryfalse
      Invariantsele-1: All FHIR elements must have a @value or children (hasValue() or (children().count() > id.count()))
      60. CodeSystem.concept.property.value[x]
      Definition

      The value of this property.

      ShortValue of the property for this concept
      Control1..1
      TypeChoice of: code, Coding, string, integer, boolean, dateTime, decimal
      [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
      Must Supporttrue
      Must Support TypesNo must-support rules about the choice of types/profiles
      Summaryfalse
      Invariantsele-1: All FHIR elements must have a @value or children (hasValue() or (children().count() > id.count()))
      62. CodeSystem.concept.concept
      Definition

      Defines children of a concept to produce a hierarchy of concepts. The nature of the relationships is variable (is-a/contains/categorizes) - see hierarchyMeaning.

      ShortChild Concepts (is-a/contains/categorizes)
      Control0..*
      TypeSeettp://hl7.org/fhir/StructureDefinition/CodeSystem#CodeSystem.concept
      Is Modifierfalse
      Must Supporttrue
      Summaryfalse
      Invariantsele-1: All FHIR elements must have a @value or children (hasValue() or (children().count() > id.count()))