> ## Documentation Index > Fetch the complete documentation index at: https://docs.metriport.com/llms.txt > Use this file to discover all available pages before exploring further. # CodeSystem > 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. ## Properties | Name | Required | Type | Description | | ------------------- | -------- | ------------------------------------------------------------------------------------------------ | ------------------------------------------------------------------------------------------------- | | url | No | uri | Canonical identifier for this code system, represented as a URI (globally unique) (Coding.system) | | identifier | No | [Identifier](/medical-api/fhir/data-types/identifier)\[] | Additional identifier for the code system (business identifier) | | version | No | string | Business version of the code system (Coding.version) | | name | No | string | Name for this code system (computer friendly) | | title | No | string | Name for this code system (human friendly) | | status | Yes | code | draft / active / retired / unknown | | experimental | No | boolean | For testing purposes, not real usage | | date | No | dateTime | Date last changed | | publisher | No | string | Name of the publisher (organization or individual) | | contact | No | [ContactDetail](/medical-api/fhir/data-types/contactdetail)\[] | Contact details for the publisher | | description | No | markdown | Natural language description of the code system | | useContext | No | [UsageContext](/medical-api/fhir/data-types/usagecontext)\[] | The context that the content is intended to support | | jurisdiction | No | [CodeableConcept](/medical-api/fhir/data-types/codeableconcept)\[] | Intended jurisdiction for code system (if applicable) | | purpose | No | markdown | Why this code system is defined | | copyright | No | markdown | Use and/or publishing restrictions | | caseSensitive | No | boolean | If code comparison is case sensitive | | valueSet | No | canonical | Canonical reference to the value set with entire code system | | hierarchyMeaning | No | code | grouped-by / is-a / part-of / classified-with | | compositional | No | boolean | If code system defines a compositional grammar | | versionNeeded | No | boolean | If definitions are not stable | | content | Yes | code | not-present / example / fragment / complete / supplement | | supplements | No | canonical | Canonical URL of Code System this adds designations and properties to | | count | No | unsignedInt | Total concepts in the code system | | filter | No | CodeSystemFilter | Filter that can be used in a value set | | - id | No | string | Unique id for inter-element referencing | | - extension | No | [Extension](/medical-api/fhir/data-types/extension)\[] | Additional content defined by implementations | | - modifierExtension | No | [Extension](/medical-api/fhir/data-types/extension)\[] | Extensions that cannot be ignored even if unrecognized | | - code | Yes | code | Code that identifies the filter | | - description | No | string | How or why the filter is used | | - operator | Yes | code\[] | = / is-a / descendent-of / is-not-a / regex / in / not-in / generalizes / exists | | - value | Yes | string | What to use for the value | | property | No | CodeSystemProperty | Additional information supplied about each concept | | - id | No | string | Unique id for inter-element referencing | | - extension | No | [Extension](/medical-api/fhir/data-types/extension)\[] | Additional content defined by implementations | | - modifierExtension | No | [Extension](/medical-api/fhir/data-types/extension)\[] | Extensions that cannot be ignored even if unrecognized | | - code | Yes | code | Identifies the property on the concepts, and when referred to in operations | | - uri | No | uri | Formal identifier for the property | | - description | No | string | Why the property is defined, and/or what it conveys | | - type | Yes | code | code / Coding / string / integer / boolean / dateTime / decimal | | concept | No | CodeSystemConcept | Concepts in the code system | | - id | No | string | Unique id for inter-element referencing | | - extension | No | [Extension](/medical-api/fhir/data-types/extension)\[] | Additional content defined by implementations | | - modifierExtension | No | [Extension](/medical-api/fhir/data-types/extension)\[] | Extensions that cannot be ignored even if unrecognized | | - code | Yes | code | Code that identifies concept | | - display | No | string | Text to display to the user | | - definition | No | string | Formal definition | | - designation | No | CodeSystemConceptDesignation | Additional representations for the concept | | - id | No | string | Unique id for inter-element referencing | | - extension | No | [Extension](/medical-api/fhir/data-types/extension)\[] | Additional content defined by implementations | | - modifierExtension | No | [Extension](/medical-api/fhir/data-types/extension)\[] | Extensions that cannot be ignored even if unrecognized | | - language | No | code | Human language of the designation | | - use | No | [Coding](/medical-api/fhir/data-types/coding) | Details how this designation would be used | | - value | Yes | string | The text value for this designation | | - property | No | CodeSystemConceptProperty | Property value for the concept | | - id | No | string | Unique id for inter-element referencing | | - extension | No | [Extension](/medical-api/fhir/data-types/extension)\[] | Additional content defined by implementations | | - modifierExtension | No | [Extension](/medical-api/fhir/data-types/extension)\[] | Extensions that cannot be ignored even if unrecognized | | - code | Yes | code | Reference to CodeSystem.property.code | | - value\[x] | Yes | code, [Coding](/medical-api/fhir/data-types/coding), string, integer, boolean, dateTime, decimal | Value of the property for this concept | | - concept | No | \[] | Child Concepts (is-a/contains/categorizes) | ## Search Parameters | Name | Type | Description | Expression | | --------------------- | --------- | --------------------------------------------------------------------------------- | --------------------------------------- | | context | token | A use context assigned to the code system | CodeSystem.useContext.value | | context-quantity | quantity | A quantity- or range-valued use context assigned to the code system | CodeSystem.useContext.value | | context-type | token | A type of use context assigned to the code system | CodeSystem.useContext.code | | date | date | The code system publication date | CodeSystem.date | | description | string | The description of the code system | CodeSystem.description | | jurisdiction | token | Intended jurisdiction for the code system | CodeSystem.jurisdiction | | name | string | Computationally friendly name of the code system | CodeSystem.name | | publisher | string | Name of the publisher of the code system | CodeSystem.publisher | | status | token | The current status of the code system | CodeSystem.status | | title | string | The human-friendly name of the code system | CodeSystem.title | | url | uri | The uri that identifies the code system | CodeSystem.url | | version | token | The business version of the code system | CodeSystem.version | | context-type-quantity | composite | A use context type and quantity- or range-based value assigned to the code system | CodeSystem.useContext | | context-type-value | composite | A use context type and value assigned to the code system | CodeSystem.useContext | | code | token | A code defined in the code system | CodeSystem.concept.code | | content-mode | token | not-present / example / fragment / complete / supplement | CodeSystem.content | | identifier | token | External identifier for the code system | CodeSystem.identifier | | language | token | A language in which a designation is provided | CodeSystem.concept.designation.language | | supplements | reference | Find code system supplements for the referenced code system | CodeSystem.supplements | | system | uri | The system for any codes defined by this code system (same as 'url') | CodeSystem.url | ## Inherited Properties | Name | Required | Type | Description | | ----------------- | -------- | ------------------------------------------------------ | ------------------------------------------------------ | | id | No | string | Logical id of this artifact | | meta | No | [Meta](/medical-api/fhir/data-types/meta) | Metadata about the resource | | implicitRules | No | uri | A set of rules under which this content was created | | language | No | code | Language of the resource content | | text | No | [Narrative](/medical-api/fhir/data-types/narrative) | Text summary of the resource, for human interpretation | | contained | No | Resource\[] | Contained, inline Resources | | extension | No | [Extension](/medical-api/fhir/data-types/extension)\[] | Additional content defined by implementations | | modifierExtension | No | [Extension](/medical-api/fhir/data-types/extension)\[] | Extensions that cannot be ignored | To view the FHIR specification for this resource, see [CodeSystem](https://www.hl7.org/fhir/StructureDefinition/CodeSystem).