FHIR R4 Current Build
This is the current officially released version of FHIR, which is R4 (v4.0.0). For a full list of all versions, see the Directory of published versions .
Vocabulary Work Group Maturity Level : N   Normative (from v4.0.0) v4.1.0) Security Category : Anonymous Compartments : Not linked to any defined compartments

Detailed Descriptions for the elements in the CodeSystem resource.

CodeSystem
Element Id CodeSystem
Definition

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.

Cardinality 0..*
Type DomainResource
Invariants
Defined on this element
csd-0 Warning 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 Rule Within a code system definition, all the codes SHALL be unique concept.code.combine($this.descendants().concept.code).isDistinct()
CodeSystem.url
Element Id 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.

Cardinality 0..1
Type uri
Requirements

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

Summary true
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.

CodeSystem.identifier
Element Id CodeSystem.identifier
Definition

A formal identifier that is used to identify this code system when it is represented in other formats, or referenced in a specification, model, design or an instance.

Note This is a business identifier, not a resource identifier (see discussion )
Cardinality 0..*
Type Identifier
Requirements

Allows externally provided and/or usable business identifiers to be easily associated with the module.

Summary true
Comments

Typically, this is used for identifiers that can go in an HL7 V3 II (instance identifier) data type, and can then identify this code system outside of FHIR, where it is not possible to use the logical URI. Note that HL7 defines at least three identifiers for many of its code systems - the FHIR canonical URL, the OID and the V2 Table 0396 mnemonic code.

CodeSystem.version
Element Id CodeSystem.version
Definition

The identifier that is used to identify this version of the code system when it is referenced in a specification, model, design or instance. This is an arbitrary value managed by the code system author and is not expected to be globally unique. For example, it might be a timestamp (e.g. yyyymmdd) if a managed version is not available. There is also no expectation that versions can be placed in a lexicographical sequence. This is used in Coding .version.

Note This is a business versionId, not a resource version id (see discussion )
Cardinality 0..1
Type string
Summary true
Comments

There may be different code system instances that have the same identifier but different versions. The version can be appended to the url in a reference to allow a reference to a particular business version of the code system with the format [url]|[version].

CodeSystem.name
Element Id 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.

Cardinality 0..1
Type string
Requirements

Support human navigation and code generation.

Summary true
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.

Invariants
Affect this element
inv-0 Warning 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}')
CodeSystem.title
Element Id CodeSystem.title
Definition

A short, descriptive, user-friendly title for the code system.

Cardinality 0..1
Type string
Summary true
Comments

This name does not need to be machine-processing friendly and may contain punctuation, white-space, etc.

CodeSystem.status
Element Id CodeSystem.status
Definition

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

Cardinality 1..1
Terminology Binding PublicationStatus ( Required )
Type code
Is Modifier true (Reason: This is labeled as "Is Modifier" because applications should not use a retired {{title}} without due consideration)
Summary true
Comments

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

CodeSystem.experimental
Element Id 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.

Cardinality 0..1
Type boolean
Requirements

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

Summary true
Comments

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

CodeSystem.date
Element Id 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.

Cardinality 0..1
Type dateTime
Alternate Names Revision Date
Summary true
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.

CodeSystem.publisher
Element Id CodeSystem.publisher
Definition

The name of the organization or individual that published the code system.

Cardinality 0..1
Type string
Requirements

Helps establish the "authority/credibility" of the code system. May also allow for contact.

Summary true
Comments

Usually an organization but may be an individual. The publisher (or steward) of the code system is the organization or individual primarily responsible for the maintenance and upkeep of the code system. This is not necessarily the same individual or organization that developed and initially authored the content. The publisher is the primary point of contact for questions or issues with the code system. This item SHOULD be populated unless the information is available from context.

CodeSystem.contact
Element Id CodeSystem.contact
Definition

Contact details to assist a user in finding and communicating with the publisher.

Cardinality 0..*
Type ContactDetail
Summary true
Comments

May be a web site, an email address, a telephone number, etc.

CodeSystem.description
Element Id CodeSystem.description
Definition

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

Cardinality 0..1
Type markdown
Alternate Names Scope; Purpose
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).

CodeSystem.useContext
Element Id CodeSystem.useContext
Definition

The content was developed with a focus and intent of supporting the contexts that are listed. These contexts may be general categories (gender, age, ...) or may be references to specific programs (insurance plans, studies, ...) and may be used to assist with indexing and searching for appropriate code system instances.

Cardinality 0..*
Type UsageContext
Requirements

Assist in searching for appropriate content.

Summary true
Comments

When multiple useContexts are specified, there is no expectation that all or any of the contexts apply.

CodeSystem.jurisdiction
Element Id CodeSystem.jurisdiction
Definition

A legal or geographic region in which the code system is intended to be used.

Cardinality 0..*
Terminology Binding Jurisdiction ( Extensible )
Type CodeableConcept
Summary true
Comments

It may be possible for the code system to be used in jurisdictions other than those for which it was originally designed or intended.

CodeSystem.purpose
Element Id CodeSystem.purpose
Definition

Explanation of why this code system is needed and why it has been designed as it has.

Cardinality 0..1
Type markdown
Comments

This element does not describe the usage of the code system. Instead, it provides traceability of ''why'' the resource is either needed or ''why'' it is defined as it is. This may be used to point to source materials or specifications that drove the structure of this code system.

CodeSystem.copyright
Element Id CodeSystem.copyright
Definition

A copyright statement relating to the code system and/or its contents. Copyright statements are generally legal restrictions on the use and publishing of the code system.

Cardinality 0..1
Type markdown
Requirements

Consumers must be able to determine any legal restrictions on the use of the code system and/or its content.

Alternate Names License; Restrictions
Comments

... Sometimes, the copyright differs between the code system and the codes that are included. The copyright statement should clearly differentiate between these when required.

CodeSystem.caseSensitive
Element Id CodeSystem.caseSensitive
Definition

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

Cardinality 0..1
Type boolean
Summary true
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.

CodeSystem.valueSet
Element Id CodeSystem.valueSet
Definition

Canonical reference to the value set that contains the entire code system.

Cardinality 0..1
Type canonical ( ValueSet )
Summary true
Comments

The definition of the value set SHALL include all codes from this code system and only codes from this code system, and it SHALL be immutable.

CodeSystem.hierarchyMeaning
Element Id CodeSystem.hierarchyMeaning
Definition

The meaning of the hierarchy of concepts as represented in this resource.

Cardinality 0..1
Terminology Binding CodeSystemHierarchyMeaning ( Required )
Type code
Summary true
Comments

Note that other representations might have a different hierarchy or none at all, and represent the information using properties.

CodeSystem.compositional
Element Id CodeSystem.compositional
Definition

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

Cardinality 0..1
Type boolean
Alternate Names grammar
Summary true
Comments

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

CodeSystem.versionNeeded
Element Id 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.

Cardinality 0..1
Type boolean
Summary true
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.

CodeSystem.content
Element Id CodeSystem.content
Definition

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

Cardinality 1..1
Terminology Binding CodeSystemContentMode ( Required )
Type code
Summary true
CodeSystem.supplements
Element Id CodeSystem.supplements
Definition

The canonical URL of the code system that this code system supplement is adding designations and properties to.

Cardinality 0..1
Type canonical ( CodeSystem )
Summary true
Comments

The most common use of a code system supplement is to add additional language support.

CodeSystem.count
Element Id CodeSystem.count
Definition

The total number of concepts defined by the code system. Where the code system has a compositional grammar, the basis of this count is defined by the system steward.

Cardinality 0..1
Type unsignedInt
Summary true
Comments

The count of concepts defined in this resource cannot be more than this value but may be less for several reasons - see the content element.

CodeSystem.filter
Element Id CodeSystem.filter
Definition

A filter that can be used in a value set compose statement when selecting concepts using a filter.

Cardinality 0..*
Summary true
Comments

Note that filters defined in code systems usually require custom code on the part of any terminology engine that will make them available for use in value set filters. For this reason, they are generally only seen in high value published terminologies.

CodeSystem.filter.code
Element Id CodeSystem.filter.code
Definition

The code that identifies this filter when it is used as a filter in ValueSet .compose.include.filter.

Cardinality 1..1
Type code
Summary true
CodeSystem.filter.description
Element Id CodeSystem.filter.description
Definition

A description of how or why the filter is used.

Cardinality 0..1
Type string
Summary true
CodeSystem.filter.operator
Element Id CodeSystem.filter.operator
Definition

A list of operators that can be used with the filter.

Cardinality 1..*
Terminology Binding FilterOperator ( Required )
Type code
Summary true
CodeSystem.filter.value
Element Id CodeSystem.filter.value
Definition

A description of what the value for the filter should be.

Cardinality 1..1
Type string
Summary true
CodeSystem.property
Element Id CodeSystem.property
Definition

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

Cardinality 0..*
Summary true
CodeSystem.property.code
Element Id 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.

Cardinality 1..1
Type code
Summary true
CodeSystem.property.uri
Element Id CodeSystem.property.uri
Definition

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

Cardinality 0..1
Type uri
Summary true
CodeSystem.property.description
Element Id CodeSystem.property.description
Definition

A description of the property- why it is defined, and how its value might be used.

Cardinality 0..1
Type string
Summary true
CodeSystem.property.type
Element Id 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).

Cardinality 1..1
Terminology Binding PropertyType ( Required )
Type code
Summary true
CodeSystem.concept
Element Id 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.

Cardinality 0..*
Comments

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

CodeSystem.concept.code
Element Id CodeSystem.concept.code
Definition

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

Cardinality 1..1
Type code
CodeSystem.concept.display
Element Id CodeSystem.concept.display
Definition

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

Cardinality 0..1
Type string
CodeSystem.concept.definition
Element Id 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.

Cardinality 0..1
Type string
CodeSystem.concept.designation
Element Id CodeSystem.concept.designation
Definition

Additional representations for the concept - other languages, aliases, specialized purposes, used for particular purposes, etc.

Cardinality 0..*
Requirements

Many concept definition systems support multiple representations, in multiple languages, and for multiple purposes.

Comments

Concepts have both a display and an array of designation . The display is equivalent to a special designation with an implied designation.use of "primary code" and a language equal to the Resource Language .

CodeSystem.concept.designation.language
Element Id CodeSystem.concept.designation.language
Definition

The language this designation is defined for.

Cardinality 0..1
Terminology Binding Common Languages ( Preferred but limited to All Languages )
Type code
Comments

In the absence of a language, the resource language applies.

CodeSystem.concept.designation.use
Element Id CodeSystem.concept.designation.use
Definition

A code that details how this designation would be used.

Cardinality 0..1
Terminology Binding Designation Use ( Extensible )
Type Coding
Comments

If no use is provided, the designation can be assumed to be suitable for general display to a human user.

CodeSystem.concept.designation.value
Element Id CodeSystem.concept.designation.value
Definition

The text value for this designation.

Cardinality 1..1
Type string
CodeSystem.concept.property
Element Id CodeSystem.concept.property
Definition

A property value for this concept.

Cardinality 0..*
CodeSystem.concept.property.code
Element Id CodeSystem.concept.property.code
Definition

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

Cardinality 1..1
Type code
CodeSystem.concept.property.value[x]
Element Id CodeSystem.concept.property.value[x]
Definition

The value of this property.

Cardinality 1..1
Type code | Coding | string | integer | boolean | dateTime | decimal
[x] Note See Choice of Data Types for further information about how to use [x]
CodeSystem.concept.concept
Element Id 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.

Cardinality 0..*
Type See CodeSystem.concept