> ## 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.

# ElementDefinition

> Base StructureDefinition for ElementDefinition Type: Captures constraints on each element within the resource, profile, or extension.

## Properties

| Name | Required | Type | Description |
| - | - | - | - |
| 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 |
| path | Yes | string | Path of the element in the hierarchy of elements |
| representation | No | code\[] | xmlAttr / xmlText / typeAttr / cdaText / xhtml |
| sliceName | No | string | Name for this particular element (in a set of slices) |
| sliceIsConstraining | No | boolean | If this slice definition constrains an inherited slice definition (or not) |
| label | No | string | Name for element to display with or prompt for element |
| code | No | [Coding](/medical-api/fhir/data-types/coding)\[] | Corresponding codes in terminologies |
| slicing | No | Element | This element is sliced - slices follow |
| - id | No | string | Unique id for inter-element referencing |
| - extension | No | [Extension](/medical-api/fhir/data-types/extension)\[] | Additional content defined by implementations |
| - discriminator | No | Element\[] | Element values that are used to distinguish the slices |
| - id | No | string | Unique id for inter-element referencing |
| - extension | No | [Extension](/medical-api/fhir/data-types/extension)\[] | Additional content defined by implementations |
| - type | Yes | code | value / exists / pattern / type / profile |
| - path | Yes | string | Path to element value |
| - description | No | string | Text description of how slicing works (or not) |
| - ordered | No | boolean | If elements must be in same order as slices |
| - rules | Yes | code | closed / open / openAtEnd |
| short | No | string | Concise definition for space-constrained presentation |
| definition | No | markdown | Full formal definition as narrative text |
| comment | No | markdown | Comments about the use of this element |
| requirements | No | markdown | Why this resource has been created |
| alias | No | string\[] | Other names |
| min | No | unsignedInt | Minimum Cardinality |
| max | No | string | Maximum Cardinality (a number or \*) |
| base | No | Element | Base definition information for tools |
| - id | No | string | Unique id for inter-element referencing |
| - extension | No | [Extension](/medical-api/fhir/data-types/extension)\[] | Additional content defined by implementations |
| - path | Yes | string | Path that identifies the base element |
| - min | Yes | unsignedInt | Min cardinality of the base element |
| - max | Yes | string | Max cardinality of the base element |
| contentReference | No | uri | Reference to definition of content for the element |
| type | No | Element\[] | Data type and Profile for this element |
| - id | No | string | Unique id for inter-element referencing |
| - extension | No | [Extension](/medical-api/fhir/data-types/extension)\[] | Additional content defined by implementations |
| - code | Yes | uri | Data type or Resource (reference to definition) |
| - profile | No | canonical\[] | Profiles (StructureDefinition or IG) - one must apply |
| - targetProfile | No | canonical\[] | Profile (StructureDefinition or IG) on the Reference/canonical target - one must apply |
| - aggregation | No | code\[] | contained / referenced / bundled - how aggregated |
| - versioning | No | code | either / independent / specific |
| defaultValue\[x] | No | base64Binary, boolean, canonical, code, date, dateTime, decimal, id, instant, integer, markdown, oid, positiveInt, string, time, unsignedInt, uri, url, uuid, [Address](/medical-api/fhir/data-types/address), [Age](/medical-api/fhir/data-types/age), [Annotation](/medical-api/fhir/data-types/annotation), [Attachment](/medical-api/fhir/data-types/attachment), [CodeableConcept](/medical-api/fhir/data-types/codeableconcept), [Coding](/medical-api/fhir/data-types/coding), [ContactPoint](/medical-api/fhir/data-types/contactpoint), [Count](/medical-api/fhir/data-types/count), [Distance](/medical-api/fhir/data-types/distance), [Duration](/medical-api/fhir/data-types/duration), [HumanName](/medical-api/fhir/data-types/humanname), [Identifier](/medical-api/fhir/data-types/identifier), [Money](/medical-api/fhir/data-types/money), [Period](/medical-api/fhir/data-types/period), [Quantity](/medical-api/fhir/data-types/quantity), [Range](/medical-api/fhir/data-types/range), [Ratio](/medical-api/fhir/data-types/ratio), Reference\<>, [SampledData](/medical-api/fhir/data-types/sampleddata), [Signature](/medical-api/fhir/data-types/signature), [Timing](/medical-api/fhir/data-types/timing), [ContactDetail](/medical-api/fhir/data-types/contactdetail), [Contributor](/medical-api/fhir/data-types/contributor), [DataRequirement](/medical-api/fhir/data-types/datarequirement), [Expression](/medical-api/fhir/data-types/expression), [ParameterDefinition](/medical-api/fhir/data-types/parameterdefinition), [RelatedArtifact](/medical-api/fhir/data-types/relatedartifact), [TriggerDefinition](/medical-api/fhir/data-types/triggerdefinition), [UsageContext](/medical-api/fhir/data-types/usagecontext), [Dosage](/medical-api/fhir/data-types/dosage), [Meta](/medical-api/fhir/data-types/meta) | Specified value if missing from instance |
| meaningWhenMissing | No | markdown | Implicit meaning when this element is missing |
| orderMeaning | No | string | What the order of the elements means |
| fixed\[x] | No | base64Binary, boolean, canonical, code, date, dateTime, decimal, id, instant, integer, markdown, oid, positiveInt, string, time, unsignedInt, uri, url, uuid, [Address](/medical-api/fhir/data-types/address), [Age](/medical-api/fhir/data-types/age), [Annotation](/medical-api/fhir/data-types/annotation), [Attachment](/medical-api/fhir/data-types/attachment), [CodeableConcept](/medical-api/fhir/data-types/codeableconcept), [Coding](/medical-api/fhir/data-types/coding), [ContactPoint](/medical-api/fhir/data-types/contactpoint), [Count](/medical-api/fhir/data-types/count), [Distance](/medical-api/fhir/data-types/distance), [Duration](/medical-api/fhir/data-types/duration), [HumanName](/medical-api/fhir/data-types/humanname), [Identifier](/medical-api/fhir/data-types/identifier), [Money](/medical-api/fhir/data-types/money), [Period](/medical-api/fhir/data-types/period), [Quantity](/medical-api/fhir/data-types/quantity), [Range](/medical-api/fhir/data-types/range), [Ratio](/medical-api/fhir/data-types/ratio), Reference\<>, [SampledData](/medical-api/fhir/data-types/sampleddata), [Signature](/medical-api/fhir/data-types/signature), [Timing](/medical-api/fhir/data-types/timing), [ContactDetail](/medical-api/fhir/data-types/contactdetail), [Contributor](/medical-api/fhir/data-types/contributor), [DataRequirement](/medical-api/fhir/data-types/datarequirement), [Expression](/medical-api/fhir/data-types/expression), [ParameterDefinition](/medical-api/fhir/data-types/parameterdefinition), [RelatedArtifact](/medical-api/fhir/data-types/relatedartifact), [TriggerDefinition](/medical-api/fhir/data-types/triggerdefinition), [UsageContext](/medical-api/fhir/data-types/usagecontext), [Dosage](/medical-api/fhir/data-types/dosage), [Meta](/medical-api/fhir/data-types/meta) | Value must be exactly this |
| pattern\[x] | No | base64Binary, boolean, canonical, code, date, dateTime, decimal, id, instant, integer, markdown, oid, positiveInt, string, time, unsignedInt, uri, url, uuid, [Address](/medical-api/fhir/data-types/address), [Age](/medical-api/fhir/data-types/age), [Annotation](/medical-api/fhir/data-types/annotation), [Attachment](/medical-api/fhir/data-types/attachment), [CodeableConcept](/medical-api/fhir/data-types/codeableconcept), [Coding](/medical-api/fhir/data-types/coding), [ContactPoint](/medical-api/fhir/data-types/contactpoint), [Count](/medical-api/fhir/data-types/count), [Distance](/medical-api/fhir/data-types/distance), [Duration](/medical-api/fhir/data-types/duration), [HumanName](/medical-api/fhir/data-types/humanname), [Identifier](/medical-api/fhir/data-types/identifier), [Money](/medical-api/fhir/data-types/money), [Period](/medical-api/fhir/data-types/period), [Quantity](/medical-api/fhir/data-types/quantity), [Range](/medical-api/fhir/data-types/range), [Ratio](/medical-api/fhir/data-types/ratio), Reference\<>, [SampledData](/medical-api/fhir/data-types/sampleddata), [Signature](/medical-api/fhir/data-types/signature), [Timing](/medical-api/fhir/data-types/timing), [ContactDetail](/medical-api/fhir/data-types/contactdetail), [Contributor](/medical-api/fhir/data-types/contributor), [DataRequirement](/medical-api/fhir/data-types/datarequirement), [Expression](/medical-api/fhir/data-types/expression), [ParameterDefinition](/medical-api/fhir/data-types/parameterdefinition), [RelatedArtifact](/medical-api/fhir/data-types/relatedartifact), [TriggerDefinition](/medical-api/fhir/data-types/triggerdefinition), [UsageContext](/medical-api/fhir/data-types/usagecontext), [Dosage](/medical-api/fhir/data-types/dosage), [Meta](/medical-api/fhir/data-types/meta) | Value must have at least these property values |
| example | No | Element\[] | Example value (as defined for type) |
| - id | No | string | Unique id for inter-element referencing |
| - extension | No | [Extension](/medical-api/fhir/data-types/extension)\[] | Additional content defined by implementations |
| - label | Yes | string | Describes the purpose of this example |
| - value\[x] | Yes | base64Binary, boolean, canonical, code, date, dateTime, decimal, id, instant, integer, markdown, oid, positiveInt, string, time, unsignedInt, uri, url, uuid, [Address](/medical-api/fhir/data-types/address), [Age](/medical-api/fhir/data-types/age), [Annotation](/medical-api/fhir/data-types/annotation), [Attachment](/medical-api/fhir/data-types/attachment), [CodeableConcept](/medical-api/fhir/data-types/codeableconcept), [Coding](/medical-api/fhir/data-types/coding), [ContactPoint](/medical-api/fhir/data-types/contactpoint), [Count](/medical-api/fhir/data-types/count), [Distance](/medical-api/fhir/data-types/distance), [Duration](/medical-api/fhir/data-types/duration), [HumanName](/medical-api/fhir/data-types/humanname), [Identifier](/medical-api/fhir/data-types/identifier), [Money](/medical-api/fhir/data-types/money), [Period](/medical-api/fhir/data-types/period), [Quantity](/medical-api/fhir/data-types/quantity), [Range](/medical-api/fhir/data-types/range), [Ratio](/medical-api/fhir/data-types/ratio), Reference\<>, [SampledData](/medical-api/fhir/data-types/sampleddata), [Signature](/medical-api/fhir/data-types/signature), [Timing](/medical-api/fhir/data-types/timing), [ContactDetail](/medical-api/fhir/data-types/contactdetail), [Contributor](/medical-api/fhir/data-types/contributor), [DataRequirement](/medical-api/fhir/data-types/datarequirement), [Expression](/medical-api/fhir/data-types/expression), [ParameterDefinition](/medical-api/fhir/data-types/parameterdefinition), [RelatedArtifact](/medical-api/fhir/data-types/relatedartifact), [TriggerDefinition](/medical-api/fhir/data-types/triggerdefinition), [UsageContext](/medical-api/fhir/data-types/usagecontext), [Dosage](/medical-api/fhir/data-types/dosage), [Meta](/medical-api/fhir/data-types/meta) | Value of Example (one of allowed types) |
| minValue\[x] | No | date, dateTime, instant, time, decimal, integer, positiveInt, unsignedInt, [Quantity](/medical-api/fhir/data-types/quantity) | Minimum Allowed Value (for some types) |
| maxValue\[x] | No | date, dateTime, instant, time, decimal, integer, positiveInt, unsignedInt, [Quantity](/medical-api/fhir/data-types/quantity) | Maximum Allowed Value (for some types) |
| maxLength | No | integer | Max length for strings |
| condition | No | id\[] | Reference to invariant about presence |
| constraint | No | Element\[] | Condition that must evaluate to true |
| - id | No | string | Unique id for inter-element referencing |
| - extension | No | [Extension](/medical-api/fhir/data-types/extension)\[] | Additional content defined by implementations |
| - key | Yes | id | Target of 'condition' reference above |
| - requirements | No | string | Why this constraint is necessary or appropriate |
| - severity | Yes | code | error / warning |
| - human | Yes | string | Human description of constraint |
| - expression | No | string | FHIRPath expression of constraint |
| - xpath | No | string | XPath expression of constraint |
| - source | No | canonical | Reference to original source of constraint |
| mustSupport | No | boolean | If the element must be supported |
| isModifier | No | boolean | If this modifies the meaning of other elements |
| isModifierReason | No | string | Reason that this element is marked as a modifier |
| isSummary | No | boolean | Include when \_summary = true? |
| binding | No | Element | ValueSet details if this is coded |
| - id | No | string | Unique id for inter-element referencing |
| - extension | No | [Extension](/medical-api/fhir/data-types/extension)\[] | Additional content defined by implementations |
| - strength | Yes | code | required / extensible / preferred / example |
| - description | No | string | Human explanation of the value set |
| - valueSet | No | canonical | Source of value set |
| mapping | No | Element\[] | Map element to another set of definitions |
| - id | No | string | Unique id for inter-element referencing |
| - extension | No | [Extension](/medical-api/fhir/data-types/extension)\[] | Additional content defined by implementations |
| - identity | Yes | id | Reference to mapping declaration |
| - language | No | code | Computable language of mapping |
| - map | Yes | string | Details of the mapping |
| - comment | No | string | Comments about the mapping or its use |


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