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FHIR Infrastructure icon Work GroupMaturity Level: NormativeStandards Status: Normative
ElementDefinition
Standards StatusThis element has a standards status of "Normative"
Element IdElementDefinition
Definition

Captures constraints on each element within the resource, profile, or extension.

Short DisplayDefinition of an element in a resource or extension
Cardinality0..*
TypeBackboneType
Summarytrue
Invariants
Defined on this element
eld-2Rule Min <= Maxmin.empty() or max.empty() or (max = '*') or iif(max != '*', min <= max.toInteger())
eld-5Rule if the element definition has a contentReference, it cannot have type, defaultValue, fixed, pattern, example, minValue, maxValue, maxLength, or bindingcontentReference.empty() or (type.empty() and defaultValue.empty() and fixed.empty() and pattern.empty() and example.empty() and minValue.empty() and maxValue.empty() and maxLength.empty() and binding.empty())
eld-6Rule Fixed value may only be specified if there is one typefixed.empty() or (type.count() <= 1)
eld-7Rule Pattern may only be specified if there is one typepattern.empty() or (type.count() <= 1)
eld-8Rule Pattern and fixed are mutually exclusivepattern.empty() or fixed.empty()
eld-11Rule Binding can only be present for coded elements, string, and uri if using FHIR-defined typesbinding.empty() or type.code.empty() or type.code.contains(":") or type.select((code = 'code') or (code = 'Coding') or (code='CodeableConcept') or (code = 'Quantity') or (code = 'string') or (code = 'uri') or (code = 'Duration')).exists()
eld-13Rule Types must be unique by codetype.select(code).isDistinct()
eld-14Rule Constraints must be unique by keyconstraint.select(key).isDistinct()
eld-15Rule default value and meaningWhenMissing are mutually exclusivedefaultValue.empty() or meaningWhenMissing.empty()
eld-16Rule sliceName must be composed of proper tokens separated by "/"sliceName.empty() or sliceName.matches('^[a-zA-Z0-9\\/\\-_\\[\\]\\@]+$')
eld-18Rule Must have a modifier reason if isModifier = true(isModifier.exists() and isModifier) implies isModifierReason.exists()
eld-19Rule Element names cannot include some special characters with a max of 64 characters,path.matches('^[^\\s\\.,:;\\\'"\\/|?!@#$%&*()\\[\\]{}]{1,64}(\\.[^\\s\\.,:;\\\'"\\/|?!@#$%&*()\\[\\]{}]{1,64}(\\[x\\])?(\\:[^\\s\\.]+)?)*$')
eld-20Warning Element names should be simple alphanumerics with a max of 64 characters or code generation tools may be brokenpath.matches('^[A-Za-z][A-Za-z0-9]{0,63}(\\.[a-z][A-Za-z0-9]{0,63}(\\[x])?)*$')
eld-22Rule sliceIsConstraining can only appear if slicename is presentsliceIsConstraining.exists() implies sliceName.exists()
eld-24Guideline pattern[x] should be used rather than fixed[x]fixed.exists().not()
This is (only) a best practice guideline because:

pattern[x] is generally preferred over fixed[x] because it doesn't preclude the use of id and additional extensions, though there are corner cases when it's appropriate to exclude those

eld-25Warning Order has no meaning (and cannot be asserted to have meaning), so enforcing rules on order is improperorderMeaning.empty() implies slicing.where(rules='openAtEnd' or ordered).exists().not()
eld-27Warning Mappings SHOULD be unique by keymapping.select(identity).isDistinct()
ElementDefinition.path
Element IdElementDefinition.path
Definition

The path identifies the element and is expressed as a "."-separated list of ancestor elements, beginning with the name of the resource or extension.

Short DisplayPath of the element in the hierarchy of elements
Cardinality1..1
Typestring
Summarytrue
ElementDefinition.representation
Element IdElementDefinition.representation
Definition

Codes that define how this element is represented in instances, when the deviation varies from the normal case. No extensions are allowed on elements with a representation of 'xmlAttr', no matter what FHIR serialization format is used.

Short DisplayxmlAttr | xmlText | typeAttr | cdaText | xhtml
Cardinality0..*
Terminology BindingPropertyRepresentation (Required)
Typecode
Summarytrue
Comments

In resources, this is rarely used except for special cases where the representation deviates from the normal, and can only be done in the base standard (and profiles must reproduce what the base standard does). This element is used quite commonly in Logical models when the logical models represent a specific serialization format (e.g. CDA, v2 etc.).

ElementDefinition.sliceName
Element IdElementDefinition.sliceName
Definition

The name of this element definition slice, when slicing is working. The name must be a token with no dots or spaces. This is a unique name referring to a specific set of constraints applied to this element, used to provide a name to different slices of the same element.

Short DisplayName for this particular element (in a set of slices)
Cardinality0..1
Typestring
Requirements

May also be used for code generation purposes.

Summarytrue
Comments

The name SHALL be unique within the structure within the context of the constrained resource element. (Though to avoid confusion, uniqueness across all elements is recommended.).

ElementDefinition.sliceIsConstraining
Element IdElementDefinition.sliceIsConstraining
Definition

If true, indicates that this slice definition is constraining a slice definition with the same name in an inherited profile. If false, the slice is not overriding any slice in an inherited profile. If missing, the slice might or might not be overriding a slice in an inherited profile, depending on the sliceName.

Short DisplayIf this slice definition constrains an inherited slice definition (or not)
Cardinality0..1
Typeboolean
Requirements

Allows detection of a situation where an ancestor profile adds or removes slicing with the same name where that might impact the child profile.

Summarytrue
Comments

If set to true, an ancestor profile SHALL have a slicing definition with this name. If set to false, no ancestor profile is permitted to have a slicing definition with this name.

ElementDefinition.label
Element IdElementDefinition.label
Definition

A single preferred label which is the text to display beside the element indicating its meaning or to use to prompt for the element in a user display or form.

Short DisplayName for element to display with or prompt for element
Cardinality0..1
Typestring
Summarytrue
Comments

See also the extension (http://hl7.org/fhir/StructureDefinition/elementdefinition-question)[extension-elementdefinition-question.html].

ElementDefinition.code
Element IdElementDefinition.code
Definition

A code that has the same meaning as the element in a particular terminology.

Short DisplayCorresponding codes in terminologies
Cardinality0..*
Terminology BindingElementDefinitionCode icon:
TypeCoding
Requirements

Links the meaning of an element to an external terminology, and is very useful for searching and indexing.

Summarytrue
Comments

The concept SHALL be properly aligned with the data element definition and other constraints, as defined in the code system, including relationships, of any code listed here. Where multiple codes exist in a terminology that could correspond to the data element, the most granular code(s) should be selected, so long as they are not more restrictive than the data element itself. The mappings may be used to provide more or less granular or structured equivalences in the code system.

ElementDefinition.slicing
Element IdElementDefinition.slicing
Definition

Indicates that the element is sliced into a set of alternative definitions (i.e. in a structure definition, there are multiple different constraints on a single element in the base resource). Slicing can be used in any resource that has cardinality ..* on the base resource, or any resource with a choice of types. The set of slices is any elements that come after this in the element sequence that have the same path, until a shorter path occurs (the shorter path terminates the set).

Short DisplayThis element is sliced - slices follow
Cardinality0..1
Summarytrue
Comments

The first element in the sequence, the one that carries the slicing, is the definition that applies to all the slices. This is based on the unconstrained element, but can apply any constraints as appropriate. This may include the common constraints on the children of the element.

ElementDefinition.slicing.discriminator
Element IdElementDefinition.slicing.discriminator
Definition

Designates which child elements are used to discriminate between the slices when processing an instance. If one or more discriminators are provided, the value of the child elements in the instance data SHALL completely distinguish which slice the element in the resource matches based on the allowed values for those elements in each of the slices.

Short DisplayElement values that are used to distinguish the slices
Cardinality0..*
Summarytrue
Comments

If there is no discriminator, the content is hard to process, so this should be avoided.

ElementDefinition.slicing.discriminator.type
Element IdElementDefinition.slicing.discriminator.type
Definition

How the element value is interpreted when discrimination is evaluated.

Short Displayvalue | exists | pattern | type | profile | position
Cardinality1..1
Terminology BindingDiscriminatorType (Required)
Typecode
Summarytrue
Comments

pattern' is deprecated - it works exactly the same as 'value'.

ElementDefinition.slicing.discriminator.path
Element IdElementDefinition.slicing.discriminator.path
Definition

A FHIRPath expression, using the simple subset of FHIRPath, that is used to identify the element on which discrimination is based.

Short DisplayPath to element value
Cardinality1..1
Typestring
Summarytrue
ElementDefinition.slicing.description
Element IdElementDefinition.slicing.description
Definition

A human-readable text description of how the slicing works. If there is no discriminator, this is required to be present to provide whatever information is possible about how the slices can be differentiated.

Short DisplayText description of how slicing works (or not)
Cardinality0..1
Typestring
Summarytrue
Comments

If it's really not possible to differentiate them, the design should be re-evaluated to make the content usable.

ElementDefinition.slicing.ordered
Element IdElementDefinition.slicing.ordered
Definition

If the matching elements have to occur in the same order as defined in the profile.

Short DisplayIf elements must be in same order as slices
Cardinality0..1
Typeboolean
Meaning if MissingOrder is not required unless specified
Summarytrue
Comments

Order should only be required when it is a pressing concern for presentation. Profile authors should consider making the order a feature of the rules about the narrative, not the rules about the data - requiring ordered data makes the profile much less re-usable.

ElementDefinition.slicing.rules
Element IdElementDefinition.slicing.rules
Definition

Whether additional slices are allowed or not. When the slices are ordered, profile authors can also say that additional slices are only allowed at the end.

Short Displayclosed | open | openAtEnd
Cardinality1..1
Terminology BindingSlicingRules (Required)
Typecode
Summarytrue
Comments

Allowing additional elements makes for a much for flexible template - it's open for use in wider contexts, but also means that the content of the resource is not closed, and applications have to decide how to handle content not described by the profile.

ElementDefinition.short
Element IdElementDefinition.short
Definition

A concise description of what this element means (e.g. for use in autogenerated summaries).

Short DisplayConcise definition for space-constrained presentation
Cardinality0..1
Typestring
Summarytrue
Comments

It is easy for a different short definition to change the meaning of an element and this can have nasty downstream consequences. Please be careful when providing short definitions in a profile.

ElementDefinition.definition
Element IdElementDefinition.definition
Definition

Provides a complete explanation of the meaning of the data element for human readability. For the case of elements derived from existing elements (e.g. constraints), the definition SHALL be consistent with the base definition, but convey the meaning of the element in the particular context of use of the resource. (Note: The text you are reading is specified in ElementDefinition.definition).

Short DisplayFull formal definition as narrative text
Cardinality0..1
Typemarkdown
Requirements

To allow a user to state the usage of an element in a particular context.

Alternate NamesDescription
Summarytrue
Comments

It is easy for a different definition to change the meaning of an element and this can have nasty downstream consequences. Please be careful when providing definitions in a profile.

ElementDefinition.comment
Element IdElementDefinition.comment
Definition

Explanatory notes and implementation guidance about the data element, including notes about how to use the data properly, exceptions to proper use, etc. (Note: The text you are reading is specified in ElementDefinition.comment).

Short DisplayComments about the use of this element
Cardinality0..1
Typemarkdown
Summarytrue
Comments

If it is possible to capture usage rules using constraints, that mechanism should be used in preference to this element.

ElementDefinition.requirements
Element IdElementDefinition.requirements
Definition

This element is for traceability of why the element was created and why the constraints exist as they do. This may be used to point to source materials or specifications that drove the structure of this element.

Short DisplayWhy this resource has been created
Cardinality0..1
Typemarkdown
Summarytrue
Comments

This element does not describe the usage of the element (that's done in comments), rather it's for traceability of why the element is either needed or why the constraints exist as they do. This may be used to point to source materials or specifications that drove the structure of this data element.

ElementDefinition.alias
Element IdElementDefinition.alias
Definition

Identifies additional names by which this element might also be known.

Short DisplayOther names
Cardinality0..*
Typestring
Requirements

Allows for better easier recognition of the element by multiple communities, including international communities.

Alternate Namessynonym; other name
Summarytrue
ElementDefinition.min
Element IdElementDefinition.min
Definition

The minimum number of times this element SHALL appear in the instance.

Short DisplayMinimum Cardinality
Cardinality0..1
TypeunsignedInt
Summarytrue
Invariants
Affect this element
eld-2Rule Min <= Maxmin.empty() or max.empty() or (max = '*') or iif(max != '*', min <= max.toInteger())
ElementDefinition.max
Element IdElementDefinition.max
Definition

The maximum number of times this element is permitted to appear in the instance.

Short DisplayMaximum Cardinality (a number or *)
Cardinality0..1
Typestring
Summarytrue
Invariants
Defined on this element
eld-3Rule Max SHALL be a number or "*"empty() or ($this = '*') or (toInteger() >= 0)
Affect this element
eld-2Rule Min <= Maxmin.empty() or max.empty() or (max = '*') or iif(max != '*', min <= max.toInteger())
ElementDefinition.base
Element IdElementDefinition.base
Definition

Information about the base definition of the element, provided to make it unnecessary for tools to trace the deviation of the element through the derived and related profiles. When the element definition is not the original definition of an element - i.g. either in a constraint on another type, or for elements from a super type in a snap shot - then the information in provided in the element definition may be different to the base definition. On the original definition of the element, it will be same.

Short DisplayBase definition information for tools
Cardinality0..1
Summarytrue
Comments

The base information does not carry any information that could not be determined from the path and related profiles, but making this determination requires both that the related profiles are available, and that the algorithm to determine them be available. For tooling simplicity, the base information must always be populated in element definitions in snap shots, even if it is the same.

ElementDefinition.base.path
Element IdElementDefinition.base.path
Definition

The Path that identifies the base element - this matches the ElementDefinition.path for that element. Across FHIR, there is only one base definition of any element - that is, an element definition on a StructureDefinition without a StructureDefinition.base.

Short DisplayPath that identifies the base element
Cardinality1..1
Typestring
Summarytrue
ElementDefinition.base.min
Element IdElementDefinition.base.min
Definition

Minimum cardinality of the base element identified by the path.

Short DisplayMin cardinality of the base element
Cardinality1..1
TypeunsignedInt
Summarytrue
Comments

This is provided for consistency with max, and may affect code generation of mandatory elements of the base resource are generated differently (some reference implementations have done this).

ElementDefinition.base.max
Element IdElementDefinition.base.max
Definition

Maximum cardinality of the base element identified by the path.

Short DisplayMax cardinality of the base element
Cardinality1..1
Typestring
Summarytrue
Comments

This is provided to code generation, since the serialization representation in JSON differs depending on whether the base element has max > 1. Also, some forms of code generation may differ.

ElementDefinition.contentReference
Element IdElementDefinition.contentReference
Definition

Identifies an element defined elsewhere in the definition whose content rules should be applied to the current element. ContentReferences bring across all the rules that are in the ElementDefinition for the element, including definitions, cardinality constraints, bindings, invariants etc.

Short DisplayReference to definition of content for the element
Cardinality0..1
Typeuri
Summarytrue
Comments

ContentReferences can only be defined in specializations, not constrained types, and they cannot be changed and always reference the non-constrained definition.

Invariants
Affect this element
eld-5Rule if the element definition has a contentReference, it cannot have type, defaultValue, fixed, pattern, example, minValue, maxValue, maxLength, or bindingcontentReference.empty() or (type.empty() and defaultValue.empty() and fixed.empty() and pattern.empty() and example.empty() and minValue.empty() and maxValue.empty() and maxLength.empty() and binding.empty())
ElementDefinition.type
Element IdElementDefinition.type
Definition

The data type or resource that the value of this element is permitted to be.

Short DisplayData type and Profile for this element
Cardinality0..*
Summarytrue
Comments

The Type of the element can be left blank in a differential constraint, in which case the type is inherited from the resource. Abstract types are not permitted to appear as a type when multiple types are listed. (I.e. Abstract types cannot be part of a choice).

Invariants
Defined on this element
eld-4Rule Aggregation may only be specified if one of the allowed types for the element is a referenceaggregation.empty() or (code = 'Reference') or (code = 'canonical') or (code = 'CodeableReference')
eld-17Rule targetProfile is only allowed if the type is Reference or canonical(code='Reference' or code = 'canonical' or code = 'CodeableReference') or targetProfile.empty()
Affect this element
eld-13Rule Types must be unique by codetype.select(code).isDistinct()
ElementDefinition.type.code
Element IdElementDefinition.type.code
Definition

URL of Data type or Resource that is a(or the) type used for this element. References are URLs that are relative to http://hl7.org/fhir/StructureDefinition e.g. "string" is a reference to http://hl7.org/fhir/StructureDefinition/string. Absolute URLs are only allowed in logical models.

Short DisplayData type or Resource (reference to definition)
Cardinality1..1
Terminology BindingElement Definition Types (Extensible)
Typeuri
Summarytrue
Comments

If the element is a reference to another resource, this element contains "Reference", and the targetProfile element defines what resources can be referenced. The targetProfile may be a reference to the general definition of a resource (e.g. http://hl7.org/fhir/StructureDefinition/Patient).

ElementDefinition.type.profile
Element IdElementDefinition.type.profile
Definition

Identifies a profile structure or implementation Guide that applies to the datatype this element refers to. If any profiles are specified, then the content must conform to at least one of them. The URL can be a local reference - to a contained StructureDefinition, or a reference to another StructureDefinition or Implementation Guide by a canonical URL. When an implementation guide is specified, the type SHALL conform to at least one profile defined in the implementation guide.

Short DisplayProfiles (StructureDefinition or IG) - one must apply
Cardinality0..*
Typecanonical(StructureDefinition | ImplementationGuide)
Summarytrue
Comments

It is possible to profile backbone element (e.g. part of a resource), using the profile-element extension.

ElementDefinition.type.targetProfile
Element IdElementDefinition.type.targetProfile
Definition

Used when the type is "Reference" or "canonical", and identifies a profile structure or implementation Guide that applies to the target of the reference this element refers to. If any profiles are specified, then the content must conform to at least one of them. The URL can be a local reference - to a contained StructureDefinition, or a reference to another StructureDefinition or Implementation Guide by a canonical URL. When an implementation guide is specified, the target resource SHALL conform to at least one profile defined in the implementation guide.

Short DisplayProfile (StructureDefinition or IG) on the Reference/canonical target - one must apply
Cardinality0..*
Typecanonical(StructureDefinition | ImplementationGuide)
Summarytrue
ElementDefinition.type.aggregation
Element IdElementDefinition.type.aggregation
Definition

If the type is a reference to another resource, how the resource is or can be aggregated - is it a contained resource, or a reference, and if the context is a bundle, is it included in the bundle.

Short Displaycontained | referenced | bundled - how aggregated
Cardinality0..*
Terminology BindingAggregationMode (Required)
Typecode
Summarytrue
Comments

See Aggregation Rules for further clarification.

Invariants
Affect this element
eld-4Rule Aggregation may only be specified if one of the allowed types for the element is a referenceaggregation.empty() or (code = 'Reference') or (code = 'canonical') or (code = 'CodeableReference')
ElementDefinition.type.versioning
Element IdElementDefinition.type.versioning
Definition

Whether this reference needs to be version specific or version independent, or whether either can be used.

Short Displayeither | independent | specific
Cardinality0..1
Terminology BindingReferenceVersionRules (Required)
Typecode
Summarytrue
Comments

The base specification never makes a rule as to which form is allowed, but implementation guides may do this. See Aggregation Rules for further clarification.

ElementDefinition.defaultValue[x]
Element IdElementDefinition.defaultValue[x]
Definition

The value that should be used if there is no value stated in the instance (e.g. 'if not otherwise specified, the abstract is false').

Short DisplaySpecified value if missing from instance
Cardinality0..1
Type*
[x] NoteSee Choice of Datatypes for further information about how to use [x]
Summarytrue
Comments

Specifying a default value means that the property can never been unknown - it must always have a value. Further, the default value can never be changed, or changed in constraints on content models. Defining default values creates many difficulties in implementation (e.g. when is a value missing?). For these reasons, default values are (and should be) used extremely sparingly.

No default values are ever defined in the FHIR specification, nor can they be defined in constraints ("profiles") on data types or resources. This element only exists so that default values may be defined in logical models.

Invariants
Affect this element
eld-15Rule default value and meaningWhenMissing are mutually exclusivedefaultValue.empty() or meaningWhenMissing.empty()
ElementDefinition.meaningWhenMissing
Element IdElementDefinition.meaningWhenMissing
Definition

The Implicit meaning that is to be understood when this element is missing (e.g. 'when this element is missing, the period is ongoing').

Short DisplayImplicit meaning when this element is missing
Cardinality0..1
Typemarkdown
Summarytrue
Comments

Implicit meanings for missing values can only be specified on a resource, data type, or extension definition, and never in a profile that applies to one of these. An implicit meaning for a missing value can never be changed, and specifying one has the consequence that constraining its use in profiles eliminates use cases as possibilities, not merely moving them out of scope.

Invariants
Affect this element
eld-15Rule default value and meaningWhenMissing are mutually exclusivedefaultValue.empty() or meaningWhenMissing.empty()
ElementDefinition.orderMeaning
Element IdElementDefinition.orderMeaning
Definition

If present, indicates that the order of the repeating element has meaning and describes what that meaning is. If absent, it means that the order of the element has no meaning.

Short DisplayWhat the order of the elements means
Cardinality0..1
Typestring
Summarytrue
Comments

This element can only be asserted on repeating elements and can only be introduced when defining resources or data types. It can be further refined profiled elements but if absent in the base type, a profile cannot assert meaning.

ElementDefinition.fixed[x]
Element IdElementDefinition.fixed[x]
Definition

Specifies a value that SHALL be exactly the value for this element in the instance, if present. For purposes of comparison, non-significant whitespace is ignored, and all values must be an exact match (case and accent sensitive). Missing elements/attributes must also be missing.

Short DisplayValue must be exactly this
Cardinality0..1
Type*
[x] NoteSee Choice of Datatypes for further information about how to use [x]
Summarytrue
Comments

This is not recommended for Coding and CodeableConcept since these often have highly contextual properties such as version or display.

Invariants
Affect this element
eld-5Rule if the element definition has a contentReference, it cannot have type, defaultValue, fixed, pattern, example, minValue, maxValue, maxLength, or bindingcontentReference.empty() or (type.empty() and defaultValue.empty() and fixed.empty() and pattern.empty() and example.empty() and minValue.empty() and maxValue.empty() and maxLength.empty() and binding.empty())
eld-6Rule Fixed value may only be specified if there is one typefixed.empty() or (type.count() <= 1)
eld-8Rule Pattern and fixed are mutually exclusivepattern.empty() or fixed.empty()
ElementDefinition.pattern[x]
Element IdElementDefinition.pattern[x]
Definition

Specifies a value that each occurrence of the element in the instance SHALL follow - that is, any value in the pattern must be found in the instance, if the element has a value. Other additional values may be found too. This is effectively constraint by example.

When pattern[x] is used to constrain a primitive, it means that the value provided in the pattern[x] must match the instance value exactly.

When an element within a pattern[x] is used to constrain an array, it means that each element provided in the pattern[x] must (recursively) match at least one element from the instance array.

When pattern[x] is used to constrain a complex object, it means that each property in the pattern must be present in the complex object, and its value must recursively match -- i.e.,

  1. If primitive: it must match exactly the pattern value
  2. If a complex object: it must match (recursively) the pattern value
  3. If an array: it must match (recursively) the pattern value

If a pattern[x] is declared on a repeating element, the pattern applies to all repetitions. If the desire is for a pattern to apply to only one element or a subset of elements, slicing must be used. See Examples of Patterns for examples of pattern usage and the effect it will have.

Short DisplayValue must have at least these property values
Cardinality0..1
Type*
[x] NoteSee Choice of Datatypes for further information about how to use [x]
Summarytrue
Comments

Mostly used for fixing values of CodeableConcept. In general, pattern[x] is not intended for use with primitive types, where is has the same meaning as fixed[x].

Invariants
Affect this element
eld-5Rule if the element definition has a contentReference, it cannot have type, defaultValue, fixed, pattern, example, minValue, maxValue, maxLength, or bindingcontentReference.empty() or (type.empty() and defaultValue.empty() and fixed.empty() and pattern.empty() and example.empty() and minValue.empty() and maxValue.empty() and maxLength.empty() and binding.empty())
eld-7Rule Pattern may only be specified if there is one typepattern.empty() or (type.count() <= 1)
eld-8Rule Pattern and fixed are mutually exclusivepattern.empty() or fixed.empty()
ElementDefinition.example
Element IdElementDefinition.example
Definition

A sample value for this element demonstrating the type of information that would typically be found in the element.

Short DisplayExample value (as defined for type)
Cardinality0..*
Summarytrue
Comments

Examples will most commonly be present for data where it's not implicitly obvious from either the data type or value set what the values might be. (I.e. Example values for dates or quantities would generally be unnecessary.) If the example value is fully populated, the publication tool can generate an instance automatically.

ElementDefinition.example.label
Element IdElementDefinition.example.label
Definition

Describes the purpose of this example amoung the set of examples.

Short DisplayDescribes the purpose of this example
Cardinality1..1
Typestring
Summarytrue
ElementDefinition.example.value[x]
Element IdElementDefinition.example.value[x]
Definition

The actual value for the element, which must be one of the types allowed for this element.

Short DisplayValue of Example (one of allowed types)
Cardinality1..1
Type*
[x] NoteSee Choice of Datatypes for further information about how to use [x]
Summarytrue
ElementDefinition.minValue[x]
Element IdElementDefinition.minValue[x]
Definition

The minimum allowed value for the element. The value is inclusive. This is allowed for the types date, dateTime, instant, time, decimal, integer, and Quantity.

Short DisplayMinimum Allowed Value (for some types)
Cardinality0..1
Typedate|dateTime|instant|time|decimal|integer|integer64|positiveInt|unsignedInt|Quantity
[x] NoteSee Choice of Datatypes for further information about how to use [x]
Summarytrue
Comments

Except for date/date/instant, the type of the minValue[x] SHALL be the same as the specified type of the element. For the date/dateTime/instant values, the type of minValue[x] SHALL be either the same, or a Duration which specifies a relative time limit to the current time. The duration value is positive, and is subtracted from the current clock to determine the minimum allowable value. A minimum value for a Quantity is interpreted as an canonical minimum - e.g. you cannot provide 100mg if the minimum value is 10g.

ElementDefinition.maxValue[x]
Element IdElementDefinition.maxValue[x]
Definition

The maximum allowed value for the element. The value is inclusive. This is allowed for the types date, dateTime, instant, time, decimal, integer, and Quantity.

Short DisplayMaximum Allowed Value (for some types)
Cardinality0..1
Typedate|dateTime|instant|time|decimal|integer|integer64|positiveInt|unsignedInt|Quantity
[x] NoteSee Choice of Datatypes for further information about how to use [x]
Summarytrue
Comments

Except for date/date/instant, the type of the maxValue[x] SHALL be the same as the specified type of the element. For the date/dateTime/instant values, the type of maxValue[x] SHALL be either the same, or a Duration which specifies a relative time limit to the current time. The duration value is positive, and is added to the current clock to determine the maximum allowable value. A maximum value for a Quantity is interpreted as an canonical maximum - e.g. you cannot provide 10g if the maximum value is 50mg.

ElementDefinition.maxLength
Element IdElementDefinition.maxLength
Definition

Indicates the maximum length in characters that is permitted to be present in conformant instances and which is expected to be supported by conformant consumers that support the element. maxLength SHOULD only be used on primitive data types that have a string representation (see Datatype characteristics).

Short DisplayMax length for string type data
Cardinality0..1
Typeinteger
Summarytrue
Comments

Receivers are not required to reject instances that exceed the maximum length. The full length could be stored. In some cases, data might be truncated, though truncation should be undertaken with care and an understanding of the consequences of doing so. If not specified, there is no conformance expectation for length support.

ElementDefinition.condition
Element IdElementDefinition.condition
Definition

A reference to an invariant that may make additional statements about the cardinality or value in the instance.

Short DisplayReference to invariant about presence
Cardinality0..*
Typeid
Summarytrue
ElementDefinition.constraint
Element IdElementDefinition.constraint
Definition

Formal constraints such as co-occurrence and other constraints that can be computationally evaluated within the context of the instance.

Short DisplayCondition that must evaluate to true
Cardinality0..*
Summarytrue
Comments

Constraints should be declared on the "context" element - the lowest element in the hierarchy that is common to all nodes referenced by the constraint.

Invariants
Defined on this element
eld-21Warning Constraints should have an expression or else validators will not be able to enforce themexpression.exists()
eld-26Rule Errors cannot be suppressed(severity = 'error') implies suppress.empty()
ElementDefinition.constraint.key
Element IdElementDefinition.constraint.key
Definition

Allows identification of which elements have their cardinalities impacted by the constraint. Will not be referenced for constraints that do not affect cardinality.

Short DisplayTarget of 'condition' reference above
Cardinality1..1
Typeid
Summarytrue
Invariants
Affect this element
eld-14Rule Constraints must be unique by keyconstraint.select(key).isDistinct()
ElementDefinition.constraint.requirements
Element IdElementDefinition.constraint.requirements
Definition

Description of why this constraint is necessary or appropriate.

Short DisplayWhy this constraint is necessary or appropriate
Cardinality0..1
Typemarkdown
Summarytrue
Comments

To be used if the reason for the constraint might not be intuitive to all implementers.

ElementDefinition.constraint.severity
Element IdElementDefinition.constraint.severity
Definition

Identifies the impact constraint violation has on the conformance of the instance.

Short Displayerror | warning
Cardinality1..1
Terminology BindingConstraintSeverity (Required)
Typecode
Summarytrue
Comments

This allows constraints to be asserted as "shall" (error) and "should" (warning).

ElementDefinition.constraint.suppress
Element IdElementDefinition.constraint.suppress
Definition

If true, indicates that the warning or best practice guideline should be suppressed.

Short DisplaySuppress warning or hint in profile
Cardinality0..1
Typeboolean
Summarytrue
Comments

This element should only be present in a derived profile where a warning or hint has been determined to be spurious/incorrect. E.g. a warning encouraging the inclusion of an element that the profile explicitly prohibits.

ElementDefinition.constraint.human
Element IdElementDefinition.constraint.human
Definition

Text that can be used to describe the constraint in messages identifying that the constraint has been violated.

Short DisplayHuman description of constraint
Cardinality1..1
Typestring
Summarytrue
Comments

Should be expressed in business terms as much as possible.

ElementDefinition.constraint.expression
Element IdElementDefinition.constraint.expression
Definition

A FHIRPath expression of constraint that can be executed to see if this constraint is met.

Short DisplayFHIRPath expression of constraint
Cardinality0..1
Typestring
Requirements

Used by validation tooling tests of the validity of the resource.

Summarytrue
Comments

In the absense of an expression, the expression is likely not enforceable by validators, and might be missed by many systems.

ElementDefinition.constraint.xpath
Element IdElementDefinition.constraint.xpath
Definition

An XPath expression of constraint that can be executed to see if this constraint is met.

Short DisplayXPath expression of constraint
Cardinality0..1
Typestring
Requirements

Used in Schematron tests of the validity of the resource.

Summarytrue
Comments

Elements SHALL use "f" as the namespace prefix for the FHIR namespace, and "x" for the xhtml namespace, and SHALL NOT use any other prefixes. Note: XPath is generally considered not useful because it does not apply to JSON and other formats and because of XSLT implementation issues, and may be removed in the future.

ElementDefinition.constraint.source
Element IdElementDefinition.constraint.source
Definition

A reference to the original source of the constraint, for traceability purposes.

Short DisplayReference to original source of constraint
Cardinality0..1
Typecanonical(StructureDefinition)
Summarytrue
Comments

This is used when, e.g. rendering, where it is not useful to present inherited constraints when rendering the snapshot.

ElementDefinition.mustSupport
Element IdElementDefinition.mustSupport
Definition

If true, implementations that produce or consume resources SHALL provide "support" for the element in some meaningful way. If false, the element may be ignored and not supported. If false, whether to populate or use the data element in any way is at the discretion of the implementation.

Short DisplayIf the element must be supported
Cardinality0..1
Typeboolean
Meaning if MissingIn a base type, where the element is being defined for the first time, the element is assumed to be mustSupport = false. In a profile (a constraint on an existing type), if mustSupport is not specific in either the differential or the snapshot, the mustSupport value is not changed from the base definition. Note, though, that the snapshot SHOULD always populate the mustSupport value
Requirements

Allows a profile to set expectations for system capabilities beyond merely respecting cardinality constraints.

Summarytrue
Comments

"Something meaningful" is context dependent and impossible to describe in the base FHIR specification. For this reason, the mustSupport flag is never set to true by the FHIR specification itself - it is only set to true in profiles. A profile on a type can always make mustSupport = true if it is false in the base type but cannot make mustSupport = false if it is true in the base type. This is done in Resource Profiles, where the profile labels an element as mustSupport=true. When a profile does this, it SHALL also make clear exactly what kind of "support" is required, as this can mean many things. Note that an element that has the property IsModifier is not necessarily a "key" element (e.g. one of the important elements to make use of the resource), nor is it automatically mustSupport - however both of these things are more likely to be true for IsModifier elements than for other elements.

ElementDefinition.isModifier
Element IdElementDefinition.isModifier
Definition

If true, the value of this element affects the interpretation of the element or resource that contains it, and the value of the element cannot be ignored. Typically, this is used for status, negation and qualification codes. The effect of this is that the element cannot be ignored by systems: they SHALL either recognize the element and process it, and/or a pre-determination has been made that it is not relevant to their particular system.

Short DisplayIf this modifies the meaning of other elements
Cardinality0..1
Typeboolean
Meaning if MissingAn element is not a modifier element unless it is explicitly specified to be one
Requirements

Allows elements to be introduced into a specification that can't safely be ignored by applications that don't recognize them.

Summarytrue
Comments

Only the definition of an element can set IsModifier true - either the specification itself or where an extension is originally defined. Once set, it cannot be changed in derived profiles. An element/extension that has isModifier=true SHOULD also have a minimum cardinality of 1, so that there is no lack of clarity about what to do if it is missing. If it can be missing, the definition SHALL make the meaning of a missing element clear.

ElementDefinition.isModifierReason
Element IdElementDefinition.isModifierReason
Definition

Explains how that element affects the interpretation of the resource or element that contains it.

Short DisplayReason that this element is marked as a modifier
Cardinality0..1
Typestring
Summarytrue
ElementDefinition.isSummary
Element IdElementDefinition.isSummary
Definition

Whether the element should be included if a client requests a search with the parameter _summary=true.

Short DisplayInclude when _summary = true?
Cardinality0..1
Typeboolean
Meaning if MissingAn element is not included in the summary unless it is explicitly specified to be so
Requirements

Allow clients to search through large resources quickly.

Summarytrue
Comments

Some resources include a set of simple metadata, and some very large data. This element is used to reduce the quantity of data returned in searches. Note that servers may pre-cache summarized resources for optimal performance. When a request is made with _summary=true, serializers only include elements marked as 'isSummary = true'. With a few exceptions (listed below), all datatype properties are included in the summary form. In resource and datatype definitions, if an element has a descendant marked as isSummary=true or if it satisfies both of the following conditions, it must be marked as isSummary=true:

  • is at the root or has a parent that is 'mustSupport'
  • has a minimum cardinality of 1 or is a modifier element

The following datatype properties are exceptions, and are not marked as isSummary:

  • Attachment.data
  • Signature.data, Signature.targetFormat, Signature.sigFormat
  • Narrative.status, Narrative.div
  • SampledData.data.
ElementDefinition.binding
Element IdElementDefinition.binding
Definition

Binds to a value set if this element is coded (code, Coding, CodeableConcept, Quantity), or the data types (string, uri).

Short DisplayValueSet details if this is coded
Cardinality0..1
Summarytrue
Comments

For a CodeableConcept, when no codes are allowed - only text, use a binding of strength "required" with a description explaining that no coded values are allowed and what sort of information to put in the "text" element.

Invariants
Defined on this element
eld-12Rule ValueSet SHALL start with http:// or https:// or urn: or #valueSet.exists() implies (valueSet.startsWith('http:') or valueSet.startsWith('https') or valueSet.startsWith('urn:') or valueSet.startsWith('#'))
eld-23Rule binding SHALL have either description or valueSetdescription.exists() or valueSet.exists()
Affect this element
eld-11Rule Binding can only be present for coded elements, string, and uri if using FHIR-defined typesbinding.empty() or type.code.empty() or type.code.contains(":") or type.select((code = 'code') or (code = 'Coding') or (code='CodeableConcept') or (code = 'Quantity') or (code = 'string') or (code = 'uri') or (code = 'Duration')).exists()
ElementDefinition.binding.strength
Element IdElementDefinition.binding.strength
Definition

Indicates the degree of conformance expectations associated with this binding - that is, the degree to which the provided value set must be adhered to in the instances.

Short Displayrequired | extensible | preferred | example
Cardinality1..1
Terminology BindingBindingStrength (Required)
Typecode
Alternate Namesconformance; extensibility
Summarytrue
Comments

For further discussion, see Using Terminologies.

ElementDefinition.binding.description
Element IdElementDefinition.binding.description
Definition

Describes the intended use of this particular set of codes.

Short DisplayIntended use of codes in the bound value set
Cardinality0..1
Typemarkdown
Summarytrue
ElementDefinition.binding.valueSet
Element IdElementDefinition.binding.valueSet
Definition

Refers to the value set that identifies the set of codes the binding refers to.

Short DisplaySource of value set
Cardinality0..1
Typecanonical(ValueSet)
Summarytrue
Comments

The reference may be version-specific or not (e.g. have a |[version] at the end of the canonical URL).

Invariants
Affect this element
eld-12Rule ValueSet SHALL start with http:// or https:// or urn: or #valueSet.exists() implies (valueSet.startsWith('http:') or valueSet.startsWith('https') or valueSet.startsWith('urn:') or valueSet.startsWith('#'))
ElementDefinition.mapping
Element IdElementDefinition.mapping
Definition

Identifies a concept from an external specification that roughly corresponds to this element.

Short DisplayMap element to another set of definitions
Cardinality0..*
Requirements

Provides guidance to implementers familiar with or converting content from other specifications.

Summarytrue
Comments

Mappings are not necessarily specific enough for safe translation.

ElementDefinition.mapping.identity
Element IdElementDefinition.mapping.identity
Definition

An internal reference to the definition of a mapping.

Short DisplayReference to mapping declaration
Cardinality1..1
Typeid
Summarytrue
ElementDefinition.mapping.language
Element IdElementDefinition.mapping.language
Definition

Identifies the computable language in which mapping.map is expressed.

Short DisplayComputable language of mapping
Cardinality0..1
Terminology BindingMime Types (Required)
Typecode
Summarytrue
Comments

If omitted, then there can be no expectation of computational interpretation of the mapping.

ElementDefinition.mapping.map
Element IdElementDefinition.mapping.map
Definition

Expresses what part of the target specification corresponds to this element.

Short DisplayDetails of the mapping
Cardinality1..1
Typestring
Summarytrue
Comments

For most mappings, the syntax is undefined. Syntax will be provided for mappings to the RIM. Multiple mappings may be possible and may include constraints on other resource elements that identify when a particular mapping applies.

ElementDefinition.mapping.comment
Element IdElementDefinition.mapping.comment
Definition

Comments that provide information about the mapping or its use.

Short DisplayComments about the mapping or its use
Cardinality0..1
Typemarkdown
Summarytrue