R4 Ballot #1 (Mixed Normative/Trial use) Current Build
This is the FHIR R4 Mixed Normative/Trial Use Ballot #1, and the version for the Cologne Connectathon in May 2018. The current version is R3 . See the ballot introduction for details about the ballot. For a full list of available versions, see the Directory of published versions and Timelines for an explanation of STU and other statuses.
FHIR Infrastructure Work Group Maturity Level : 5 Normative Ballot Standards Status : Normative
Normative Candidate Note: This page is candidate normative content for R4 in the Infrastructure Package . Once normative, it will lose it's Maturity Level, and breaking changes will no longer be made. null LOINC Code R/O/C
ElementDefinition
Standards Status This element has a standards status of "Normative" which is different to the status of the whole resource
Element Id ElementDefinition
Definition

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

Control Cardinality 1..1 0..*
Type BackboneElement
Summary true
Invariants : min.empty() or max.empty() or (max = '*') or iif(max != '*', min <= max.toInteger()), xpath: not(exists(f:min)) or not(exists(f:max)) or (not(f:max/@value) and not(f:min/@value)) or (f:max/@value = '*') or (number(f:max/@value) >= f:min/@value))
Defined on this element
eld-2 Rule Min <= Max min.empty() or max.empty() or (max = '*') or iif(max != '*', min <= max.toInteger())
eld-5 Rule if the element definition has a contentReference, it cannot have type, defaultValue, fixed, pattern, example, minValue, maxValue, maxLength, or binding contentReference.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-6 Rule Fixed value may only be specified if there is one type fixed.empty() or (type.count() <= 1)
eld-7 Rule Pattern may only be specified if there is one type pattern.empty() or (type.count() <= 1)
eld-8 Rule Pattern and value are mutually exclusive pattern.empty() or fixed.empty()
eld-11 : Rule Binding can only be present for coded elements, string, and uri ( expression : binding.empty() or type.code.empty() or type.select((code = 'code') or (code = 'Coding') or (code='CodeableConcept') or (code = 'Quantity') or (code = 'string') or (code = 'uri')).exists(), xpath: not(exists(f:binding)) or (count(f:type/f:code) = 0) or f:type/f:code/@value=('code','Coding','CodeableConcept','Quantity','string', 'uri')) 'uri')).exists()
eld-13 : Rule Types must be unique by code ( expression : type.select(code).isDistinct(), xpath: not(exists(for $type in f:type return $type/preceding-sibling::f:type[f:code/@value=$type/f:code/@value))) type.select(code).isDistinct()
eld-14 : Rule Constraints must be unique by key ( expression : constraint.select(key).isDistinct(), xpath: count(f:constraint) = count(distinct-values(f:constraint/f:key/@value))) constraint.select(key).isDistinct()
eld-15 : Rule default value and meaningWhenMissing are mutually exclusive ( expression : defaultValue.empty() or meaningWhenMissing.empty(), xpath: not(exists(f:*[starts-with(local-name(.), 'fixed')])) or not(exists(f:meaningWhenMissing))) meaningWhenMissing.empty()
eld-16 : Rule sliceName must be composed of proper tokens separated by "/" ( expression : sliceName.empty() or sliceName.matches('^[a-zA-Z0-9\\/\\-_\\[\\]\\@]+$'), xpath: not(exists(f:sliceName/@value)) or matches(f:sliceName/@value, '^[a-zA-Z0-9\/\-_\[\]\@]+$')) sliceName.matches('^[a-zA-Z0-9\\/\\-_\\[\\]\\@]+$')
eld-18 : Rule Must have a modifier reason if isModifier = true ( expression : isModifier implies isModifierReason.exists(), xpath: not(f:isModifier/@value = 'true') or exists(f:isModifierReason)) isModifierReason.exists() eld-2 : Min <= Max ( expression
eld-5 : if the element definition has a contentReference, it eld-19 Rule Element names cannot have type, defaultValue, fixed, pattern, example, minValue, maxValue, maxLength, or binding ( expression include some special characters : contentReference.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()), xpath: not(exists(f:contentReference) and (exists(f:type) or exists(f:*[starts-with(local-name(.), 'value')]) or exists(f:*[starts-with(local-name(.), 'defaultValue')]) or exists(f:*[starts-with(local-name(.), 'fixed')]) or exists(f:*[starts-with(local-name(.), 'pattern')]) or exists(f:*[starts-with(local-name(.), 'example')]) or exists(f:*[starts-with(local-name(.), 'f:minValue')]) or exists(f:*[starts-with(local-name(.), 'f:maxValue')]) or exists(f:maxLength) or exists(f:binding)))) path.matches('[^\\s\\.,:;\\\'"\\/|?!@#$%&*()\\[\\]{}]{1,64}(\\.[^\\s\\.,:;\\\'"\\/|?!@#$%&*()\\[\\]{}]{1,64}(\\[x\\])?(\\:[^\\s\\.]+)?)*')
eld-6 : Fixed value eld-20 Warning Element names should be simple alphanumerics with a max of 64 characters, or code generation tools may only be specified if there is one type ( expression broken : fixed.empty() or (type.count() <= 1), xpath: not(exists(f:*[starts-with(local-name(.), 'fixed')])) or (count(f:type)<=1)) path.matches('[A-Za-z][A-Za-z0-9]*(\\.[a-z][A-Za-z0-9]*(\\[x])?)*')
eld-7 : Pattern may eld-22 Rule sliceIsConstraining can only be specified appear if there slicename is one type ( expression : pattern.empty() or (type.count() <= 1), xpath: not(exists(f:*[starts-with(local-name(.), 'pattern')])) or (count(f:type)<=1)) present eld-8 : Pattern and value are mutually exclusive ( expression sliceIsConstraining.exists() implies sliceName.exists() : pattern.empty() or fixed.empty(), xpath: not(exists(f:*[starts-with(local-name(.), 'pattern')])) or not(exists(f:*[starts-with(local-name(.), 'fixed')])))
ElementDefinition.path
Element Id ElementDefinition.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.

Control Cardinality 1..1
Type string
Summary true
ElementDefinition.representation
Element Id ElementDefinition.representation
Definition

Codes that define how this element is represented in instances, when the deviation varies from the normal case.

Control Cardinality 0..*
Terminology Binding PropertyRepresentation ( Required )
Type code
Summary true
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 Id ElementDefinition.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.

Control Cardinality 0..1
Type string
Requirements

May also be used for code generation purposes.

Summary true
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 Id ElementDefinition.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.

Cardinality 0..1
Type boolean
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.

Summary true
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 Id ElementDefinition.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.

Control Cardinality 0..1
Type string
Summary true
Comments

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

ElementDefinition.code
Element Id ElementDefinition.code
Definition

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

Control Cardinality 0..*
Terminology Binding LOINC Codes ( Example )
Type Coding
Requirements

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

Summary true
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.

LOINC Code LOINC_NUM
ElementDefinition.slicing
Element Id ElementDefinition.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).

Control Cardinality 0..1
Summary true
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.

Invariants
Defined on this element
eld-1 : Rule If there are no discriminators, there must be a definition ( expression : discriminator.exists() or description.exists(), xpath: (f:discriminator) or (f:description)) description.exists()
ElementDefinition.slicing.discriminator
Element Id ElementDefinition.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.

Control Cardinality 0..*
Summary true
Comments

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

ElementDefinition.slicing.discriminator.type
Element Id ElementDefinition.slicing.discriminator.type
Definition

How the element value is interpreted when discrimination is evaluated.

Control Cardinality 1..1
Terminology Binding DiscriminatorType ( Required )
Type code
Summary true
ElementDefinition.slicing.discriminator.path
Element Id ElementDefinition.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.

Control Cardinality 1..1
Type string
Summary true
Comments

The only FHIRPath functions that are allowed are as(type), resolve(), and extension(url).

ElementDefinition.slicing.description
Element Id ElementDefinition.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.

Control Cardinality 0..1
Type string
Summary true
Comments

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

Invariants
Affect this element
eld-1 : Rule If there are no discriminators, there must be a definition ( expression : discriminator.exists() or description.exists(), xpath: (f:discriminator) or (f:description)) description.exists()
ElementDefinition.slicing.ordered
Element Id ElementDefinition.slicing.ordered
Definition

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

Control Cardinality 0..1
Type boolean
Meaning if Missing Order is not required unless specified
Summary true
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 Id ElementDefinition.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.

Control Cardinality 1..1
Terminology Binding SlicingRules ( Required )
Type code
Summary true
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 Id ElementDefinition.short
Definition

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

Control Cardinality 0..1
Type string
Summary true
Comments

May change the term to provide language more appropriate It is easy for a different short definition to change the context meaning of the profile or to reflect slicing. an element and this can have nasty downstream consequences. Please be careful when providing short definitions in a profile.

ElementDefinition.definition
Element Id ElementDefinition.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).

Control Cardinality 0..1
Type markdown
Requirements

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

Alternate Names Description
Summary true
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. definitions in a profile.

LOINC Code TERM DEFINITION/DESCRIPTION(S)
ElementDefinition.comment
Element Id ElementDefinition.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).

Control Cardinality 0..1
Type markdown
Summary true
Comments

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

LOINC Code COMMENTS
ElementDefinition.requirements
Element Id ElementDefinition.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.

Control Cardinality 0..1
Type markdown
Summary true
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 Id ElementDefinition.alias
Definition

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

Control Cardinality 0..*
Type string
Requirements

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

Alternate Names synonym; other name
Summary true
LOINC Code RELATED NAMES (only some of these apply)
ElementDefinition.min
Element Id ElementDefinition.min
Definition

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

Control Cardinality 0..1
Type unsignedInt
Summary true
Invariants
Affect this element
eld-2 : Rule Min <= Max ( expression : min.empty() or max.empty() or (max = '*') or iif(max != '*', min <= max.toInteger()), xpath: not(exists(f:min)) or not(exists(f:max)) or (not(f:max/@value) and not(f:min/@value)) or (f:max/@value = '*') or (number(f:max/@value) >= f:min/@value)) max.toInteger())
ElementDefinition.max
Element Id ElementDefinition.max
Definition

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

Control Cardinality 0..1
Type string
Summary true
Invariants
Defined on this element
eld-3 : Rule Max SHALL be a number or "*" ( expression : empty() or ($this = '*') or (toInteger() >= 0), xpath: @value='*' or (normalize-space(@value)!='' and normalize-space(translate(@value, '0123456789',''))='')) 0)
Affect this element
eld-2 : Rule Min <= Max ( expression : min.empty() or max.empty() or (max = '*') or iif(max != '*', min <= max.toInteger()), xpath: not(exists(f:min)) or not(exists(f:max)) or (not(f:max/@value) and not(f:min/@value)) or (f:max/@value = '*') or (number(f:max/@value) >= f:min/@value)) max.toInteger())
ElementDefinition.base
Element Id ElementDefinition.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.

Control Cardinality 0..1
Summary true
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 Id ElementDefinition.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.

Control Cardinality 1..1
Type string
Summary true
ElementDefinition.base.min
Element Id ElementDefinition.base.min
Definition

Minimum cardinality of the base element identified by the path.

Control Cardinality 1..1
Type unsignedInt
Summary true
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 Id ElementDefinition.base.max
Definition

Maximum cardinality of the base element identified by the path.

Control Cardinality 1..1
Type string
Summary true
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 Id ElementDefinition.contentReference
Definition

Identifies the identity of an element defined elsewhere in the profile 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.

Control Cardinality 0..1
Type uri
Summary true
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-5 : Rule if the element definition has a contentReference, it cannot have type, defaultValue, fixed, pattern, example, minValue, maxValue, maxLength, or binding ( expression : contentReference.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()), xpath: not(exists(f:contentReference) and (exists(f:type) or exists(f:*[starts-with(local-name(.), 'value')]) or exists(f:*[starts-with(local-name(.), 'defaultValue')]) or exists(f:*[starts-with(local-name(.), 'fixed')]) or exists(f:*[starts-with(local-name(.), 'pattern')]) or exists(f:*[starts-with(local-name(.), 'example')]) or exists(f:*[starts-with(local-name(.), 'f:minValue')]) or exists(f:*[starts-with(local-name(.), 'f:maxValue')]) or exists(f:maxLength) or exists(f:binding)))) binding.empty())
ElementDefinition.type
Element Id ElementDefinition.type
Definition

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

Control Cardinality 0..*
Summary true
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 : code='Reference' or targetProfile.empty(), xpath: not(exists(f:targetProfile)) or (f:code/@value = 'Reference'))
Defined on this element eld-17 : targetProfie is only allowed if the type is reference ( expression
eld-4 : Rule Aggregation may only be specified if one of the allowed types for the element is a reference ( expression : aggregation.empty() or (code = 'Reference'), xpath: not(exists(f:aggregation)) 'Reference')
eld-17 Rule targetProfile is only allowed if the type is Reference or exists(f:code[@value canonical (code='Reference' or code = 'Reference'])) 'canonical') or targetProfile.empty()
Affect this element
eld-13 : Rule Types must be unique by code ( expression : type.select(code).isDistinct(), xpath: not(exists(for $type in f:type return $type/preceding-sibling::f:type[f:code/@value=$type/f:code/@value))) type.select(code).isDistinct()
LOINC Code HL7_V2_DATATYPE (translation required), HL7_V3_DATATYPE (translation required)
ElementDefinition.type.code
Element Id ElementDefinition.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.

Control Cardinality 1..1
Terminology Binding FHIRDefinedType ( Extensible )
Type uri
Summary true
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).

LOINC Code HL7_V2_DATATYPE (translation required), HL7_V3_DATATYPE (translation required)
ElementDefinition.type.profile
Element Id ElementDefinition.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.

Control Cardinality 0..*
Type canonical ( StructureDefinition | ImplementationGuide )
Summary true
Comments

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

ElementDefinition.type.targetProfile
Element Id ElementDefinition.type.targetProfile
Definition

Used when the type is "Reference", "Reference" or "canonical", and Identifies 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.

Control Cardinality 0..*
Type canonical ( StructureDefinition | ImplementationGuide )
Summary true
ElementDefinition.type.aggregation
Element Id ElementDefinition.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.

Control Cardinality 0..*
Terminology Binding AggregationMode ( Required )
Type code
Summary true
Comments

See Aggregation Rules for further clarification.

Invariants
Affect this element
eld-4 : Rule Aggregation may only be specified if one of the allowed types for the element is a reference ( expression : aggregation.empty() or (code = 'Reference'), xpath: not(exists(f:aggregation)) or exists(f:code[@value = 'Reference'])) 'Reference')
ElementDefinition.type.versioning
Element Id ElementDefinition.type.versioning
Definition

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

Control Cardinality 0..1
Terminology Binding ReferenceVersionRules ( Required )
Type code
Summary true
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 Id ElementDefinition.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').

Control Cardinality 0..1
Type *
[x] Note See Choice of Data Types for further information about how to use [x]
Summary true
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-15 : Rule default value and meaningWhenMissing are mutually exclusive ( expression : defaultValue.empty() or meaningWhenMissing.empty(), xpath: not(exists(f:*[starts-with(local-name(.), 'fixed')])) or not(exists(f:meaningWhenMissing))) meaningWhenMissing.empty()
ElementDefinition.meaningWhenMissing
Element Id ElementDefinition.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'. ongoing').

Control Cardinality 0..1
Type markdown
Summary true
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-15 : Rule default value and meaningWhenMissing are mutually exclusive ( expression : defaultValue.empty() or meaningWhenMissing.empty(), xpath: not(exists(f:*[starts-with(local-name(.), 'fixed')])) or not(exists(f:meaningWhenMissing))) meaningWhenMissing.empty()
ElementDefinition.orderMeaning
Element Id ElementDefinition.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.

Control Cardinality 0..1
Type string
Summary true
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 Id ElementDefinition.fixed[x]
Definition

Specifies a value that SHALL be exactly the value for this element in the instance. 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.

Control Cardinality 0..1
Type *
[x] Note See Choice of Data Types for further information about how to use [x]
Summary true
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-5 : Rule if the element definition has a contentReference, it cannot have type, defaultValue, fixed, pattern, example, minValue, maxValue, maxLength, or binding ( expression : contentReference.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()), xpath: not(exists(f:contentReference) and (exists(f:type) or exists(f:*[starts-with(local-name(.), 'value')]) or exists(f:*[starts-with(local-name(.), 'defaultValue')]) or exists(f:*[starts-with(local-name(.), 'fixed')]) or exists(f:*[starts-with(local-name(.), 'pattern')]) or exists(f:*[starts-with(local-name(.), 'example')]) or exists(f:*[starts-with(local-name(.), 'f:minValue')]) or exists(f:*[starts-with(local-name(.), 'f:maxValue')]) or exists(f:maxLength) or exists(f:binding)))) binding.empty())
eld-6 : Rule Fixed value may only be specified if there is one type ( expression : fixed.empty() or (type.count() <= 1), xpath: not(exists(f:*[starts-with(local-name(.), 'fixed')])) or (count(f:type)<=1)) 1)
eld-8 : Rule Pattern and value are mutually exclusive ( expression : pattern.empty() or fixed.empty(), xpath: not(exists(f:*[starts-with(local-name(.), 'pattern')])) or not(exists(f:*[starts-with(local-name(.), 'fixed')]))) fixed.empty()
ElementDefinition.pattern[x]
Element Id ElementDefinition.pattern[x]
Definition

Specifies a value that the value in the instance SHALL follow - that is, any value in the pattern must be found in the instance. Other additional values may be found too. This is effectively constraint by example. The values of elements present

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 pattern[x] is used to constrain an array, it means that each element provided in the pattern[x] array 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 exactly (case-sensitive, accent-sensitive, etc.). -- 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.
Control Cardinality 0..1
Type *
[x] Note See Choice of Data Types for further information about how to use [x]
Summary true
Comments

Mostly used for fixing values of CodeableConcept. At present, In general, pattern[x] is not recommended as a basis intended for slicing while issues related to this are investigated during use with primitive types, where is has the STU period. same meaning as fixed[x].

Invariants
Affect this element
eld-5 : Rule if the element definition has a contentReference, it cannot have type, defaultValue, fixed, pattern, example, minValue, maxValue, maxLength, or binding ( expression : contentReference.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()), xpath: not(exists(f:contentReference) and (exists(f:type) or exists(f:*[starts-with(local-name(.), 'value')]) or exists(f:*[starts-with(local-name(.), 'defaultValue')]) or exists(f:*[starts-with(local-name(.), 'fixed')]) or exists(f:*[starts-with(local-name(.), 'pattern')]) or exists(f:*[starts-with(local-name(.), 'example')]) or exists(f:*[starts-with(local-name(.), 'f:minValue')]) or exists(f:*[starts-with(local-name(.), 'f:maxValue')]) or exists(f:maxLength) or exists(f:binding)))) binding.empty())
eld-7 : Rule Pattern may only be specified if there is one type ( expression : pattern.empty() or (type.count() <= 1), xpath: not(exists(f:*[starts-with(local-name(.), 'pattern')])) or (count(f:type)<=1)) 1)
eld-8 : Rule Pattern and value are mutually exclusive ( expression : pattern.empty() or fixed.empty(), xpath: not(exists(f:*[starts-with(local-name(.), 'pattern')])) or not(exists(f:*[starts-with(local-name(.), 'fixed')]))) fixed.empty()
ElementDefinition.example
Element Id ElementDefinition.example
Definition

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

Control Cardinality 0..*
Summary true
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 Id ElementDefinition.example.label
Definition

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

Control Cardinality 1..1
Type string
Summary true
ElementDefinition.example.value[x]
Element Id ElementDefinition.example.value[x]
Definition

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

Control Cardinality 1..1
Type *
[x] Note See Choice of Data Types for further information about how to use [x]
Summary true
LOINC Code EXMPL_ANSWERS
ElementDefinition.minValue[x]
Element Id ElementDefinition.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.

Control Cardinality 0..1
Type date | dateTime | instant | time | decimal | integer | positiveInt | unsignedInt | Quantity
[x] Note See Choice of Data Types for further information about how to use [x]
Summary true
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 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 Id ElementDefinition.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.

Control Cardinality 0..1
Type date | dateTime | instant | time | decimal | integer | positiveInt | unsignedInt | Quantity
[x] Note See Choice of Data Types for further information about how to use [x]
Summary true
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 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 Id ElementDefinition.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.

Control Cardinality 0..1
Type integer
Summary true
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 Id ElementDefinition.condition
Definition

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

Control Cardinality 0..*
Type id
Summary true
ElementDefinition.constraint
Element Id ElementDefinition.constraint
Definition

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

Control Cardinality 0..*
Summary true
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-21 Warning Constraints should have an expression or else validators will not be able to enforce them expression.exists()
ElementDefinition.constraint.key
Element Id ElementDefinition.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.

Control Cardinality 1..1
Type id
Summary true
Invariants
Affect this element
eld-14 : Rule Constraints must be unique by key ( expression : constraint.select(key).isDistinct(), xpath: count(f:constraint) = count(distinct-values(f:constraint/f:key/@value))) constraint.select(key).isDistinct()
ElementDefinition.constraint.requirements
Element Id ElementDefinition.constraint.requirements
Definition

Description of why this constraint is necessary or appropriate.

Control Cardinality 0..1
Type string
Summary true
Comments

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

ElementDefinition.constraint.severity
Element Id ElementDefinition.constraint.severity
Definition

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

Control Cardinality 1..1
Terminology Binding ConstraintSeverity ( Required )
Type code
Summary true
Comments

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

ElementDefinition.constraint.human
Element Id ElementDefinition.constraint.human
Definition

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

Control Cardinality 1..1
Type string
Summary true
Comments

Should be expressed in business terms as much as possible.

ElementDefinition.constraint.expression
Element Id ElementDefinition.constraint.expression
Definition

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

Control Cardinality 1..1 0..1
Type string
Requirements

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

Summary true
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 Id ElementDefinition.constraint.xpath
Definition

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

Control Cardinality 0..1
Type string
Requirements

Used in Schematron tests of the validity of the resource.

Summary true
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: we are considering deprecating the xpath element. Implementer feedback XPath is welcome. 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 Id ElementDefinition.constraint.source
Definition

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

Control Cardinality 0..1
Type canonical ( StructureDefinition )
Summary true
Comments

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

ElementDefinition.mustSupport
Element Id ElementDefinition.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.

Control Cardinality 0..1
Type boolean
Meaning if Missing In 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 differentil or the snapshot, the mustSupport value is not changed fro the base definition. Not, though, that the snapshot SHOULD always populate the mustSuppot value
Requirements

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

Summary true
Comments

"Something useful" is context dependent and impossible to describe in the base FHIR specification. For this reason, tue 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 musSupport = 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 Id ElementDefinition.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.

Control Cardinality 0..1
Type boolean
Meaning if Missing An element is not a modified 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.

Summary true
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 Id ElementDefinition.isModifierReason
Definition

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

Control Cardinality 0..1
Type string
Summary true
ElementDefinition.isSummary
Element Id ElementDefinition.isSummary
Definition

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

Control Cardinality 0..1
Type boolean
Meaning if Missing An element is not included in the summary unless it is explicitly specified to be so
Requirements

Allow clients to search through large resources quickly.

Summary true
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, so servers might not support per-profile use of the isSummary flag. When a request is made with _summary=true, serailisers only include elements marked as 'isSummary = true'. Other than Attachment.data, all data type properties are included in the summary form. Modifier elements In resource and data type definitions, if an element is at the root or elements with has a parent that is 'mustSupport' and the minimum cardinality = is 1 or the element is a modifier, it must be marked as summary elements. isSummary=true.

ElementDefinition.binding
Element Id ElementDefinition.binding
Definition

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

Control Cardinality 0..1
Summary true
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-12 : Rule ValueSet as a URI SHALL start with http:// or https:// or urn: ( expression : (valueSet is uri).not() or (valueSet as uri).startsWith('http:') or (valueSet as uri).startsWith('https') or (valueSet as uri).startsWith('urn:'), xpath: not(exists(f:valueSetUri)) or (starts-with(string(f:valueSetUri/@value), 'http:') valueSet.exists() implies (valueSet.startsWith('http:') or starts-with(string(f:valueSetUri/@value), 'https:') valueSet.startsWith('https') or starts-with(string(f:valueSetUri/@value), 'urn:'))) valueSet.startsWith('urn:'))
Affect this element
eld-11 : Rule Binding can only be present for coded elements, string, and uri ( expression : binding.empty() or type.code.empty() or type.select((code = 'code') or (code = 'Coding') or (code='CodeableConcept') or (code = 'Quantity') or (code = 'string') or (code = 'uri')).exists(), xpath: not(exists(f:binding)) or (count(f:type/f:code) = 0) or f:type/f:code/@value=('code','Coding','CodeableConcept','Quantity','string', 'uri')) 'uri')).exists()
LOINC Code ANSWER LIST, NORMATIVE ANSWER LIST
ElementDefinition.binding.strength
Element Id ElementDefinition.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.

Control Cardinality 1..1
Terminology Binding BindingStrength ( Required )
Type code
Alternate Names conformance; extensibility
Summary true
Comments

For further discussion, see Using Terminologies .

LOINC Code N/A
ElementDefinition.binding.description
Element Id ElementDefinition.binding.description
Definition

Describes the intended use of this particular set of codes.

Control Cardinality 0..1
Type string
Summary true
ElementDefinition.binding.valueSet[x] ElementDefinition.binding.valueSet
Element Id ElementDefinition.binding.valueSet[x] ElementDefinition.binding.valueSet
Definition

Points Refers to the value set or external definition (e.g. implicit value set) that identifies the set of codes to be used. If the binding refers to an explicit value set - the normal case - then use a canonical(ValueSet) preferably containing the canonical URL for the value set. If the reference is to an implicit value set - usually, an IETF RFC that defines a grammar, such as mime types - then use a uri. to.

Control Cardinality 0..1
Type uri | canonical ( ValueSet )
[x] Note See Choice of Data Types for further information about how to use [x] Summary true
Comments

For value sets with a referenceResource, the display can contain the value set description. The reference may be version-specific or not. not (e.g. have a |[version] at the end of the canonical URL).

Invariants
Affect this element
eld-12 : Rule ValueSet as a URI SHALL start with http:// or https:// or urn: ( expression : (valueSet is uri).not() or (valueSet as uri).startsWith('http:') or (valueSet as uri).startsWith('https') or (valueSet as uri).startsWith('urn:'), xpath: not(exists(f:valueSetUri)) or (starts-with(string(f:valueSetUri/@value), 'http:') valueSet.exists() implies (valueSet.startsWith('http:') or starts-with(string(f:valueSetUri/@value), 'https:') valueSet.startsWith('https') or starts-with(string(f:valueSetUri/@value), 'urn:'))) valueSet.startsWith('urn:'))
LOINC Code CODE_TABLE
ElementDefinition.mapping
Element Id ElementDefinition.mapping
Definition

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

Control Cardinality 0..*
Requirements

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

Summary true
Comments

Mappings are not necessarily specific enough for safe translation.

ElementDefinition.mapping.identity
Element Id ElementDefinition.mapping.identity
Definition

An internal reference to the definition of a mapping.

Control Cardinality 1..1
Type id
Summary true
ElementDefinition.mapping.language
Element Id ElementDefinition.mapping.language
Definition

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

Control Cardinality 0..1
Terminology Binding MimeType : ( Required )
Type code
Summary true
Comments

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

ElementDefinition.mapping.map
Element Id ElementDefinition.mapping.map
Definition

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

Control Cardinality 1..1
Type string
Summary true
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 Id ElementDefinition.mapping.comment
Definition

Comments that provide information about the mapping or its use.

Control Cardinality 0..1
Type string
Summary true