Name Flags Card. Type Description & Constraints ElementDefinition ΣN Element Definition of an element in a resource or extension + Rule: Min <= Max + Rule: if the element definition has a contentReference, it cannot have type, defaultValue, fixed, pattern, example, minValue, maxValue, maxLength, or binding + Rule: Fixed value may only be specified if there is one type + Rule: Pattern may only be specified if there is one type + Rule: Pattern and fixed are mutually exclusive + Rule: Binding can only be present for coded elements, string, and uri if using FHIR-defined types + Rule: Types must be unique by code + Rule: Constraints must be unique by key + Rule: default value and meaningWhenMissing are mutually exclusive + Rule: sliceName must be composed of proper tokens separated by "/" + Rule: Must have a modifier reason if isModifier = true + Rule: Element path SHALL be expressed as a set of '.'-separated components with each component restricted to a maximum of 64 characters and with some limits on the allowed choice of characters + Warning: The first component of the path should be UpperCamelCase. Additional components (following a '.') should be lowerCamelCase. If this syntax is not adhered to, code generation tools may be broken. Logical models may be less concerned about this implication. + Rule: sliceIsConstraining can only appear if slicename is present + Guideline: pattern[x] should be used rather than fixed[x] + Warning: Order has no meaning (and cannot be asserted to have meaning), so enforcing rules on order is improper + Warning: Mappings SHOULD be unique by key + Rule: Can't have valueAlternatives if mustHaveValue is true + Warning: If there's more than one bindable type, it's usually an error for there to be a binding Elements defined in Ancestors: id, <a href="types.html#Element" title="May be used to represent additional information that is not part of the basic definition of the element. To make the use of extensions safe and managable, there is a strict set of governance applied to the definition and use of extensions. Though any implementer can define an extension, there is a set of requirements that SHALL be met as part of the definition of the extension.">extension, <a href="types.html#BackboneType" title="May be used to represent additional information that is not part of the basic definition of the element and that modifies the understanding of the element in which it is contained and/or the understanding of the containing element's descendants. Usually modifier elements provide negation or qualification. To make the use of extensions safe and managable, there is a strict set of governance applied to the definition and use of extensions. Though any implementer can define an extension, there is a set of requirements that SHALL be met as part of the definition of the extension. Applications processing a resource are required to check for modifier extensions.#xA;#xA;Modifier extensions SHALL NOT change the meaning of any elements on Resource or DomainResource (including cannot change the meaning of modifierExtension itself).">modifierExtension #xD; path ΣC 1..1 string Path of the element in the hierarchy of elements #xD; representation Σ 0..* code xmlAttr | xmlText | typeAttr | cdaText | xhtml Binding: PropertyRepresentation (Required) #xD; sliceName ΣC 0..1 string Name for this particular element (in a set of slices) #xD; <a href="elementdefinition-definitions.html#ElementDefinition.sliceIsConstraining" title="ElementDefinition.sliceIsConstraining : 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.">sliceIsConstraining ΣC 0..1 boolean If this slice definition constrains an inherited slice definition (or not) #xD; label ΣT 0..1 string String to display with or prompt for element #xD; code Σ 0..* Coding Corresponding codes in terminologies Binding: ElementDefinitionCode (Example) #xD; <a href="elementdefinition-definitions.html#ElementDefinition.slicing" title="ElementDefinition.slicing : 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).">slicing ΣC 0..1 Element This element is sliced - slices follow #xD; <a href="elementdefinition-definitions.html#ElementDefinition.slicing.discriminator" title="ElementDefinition.slicing.discriminator : Designates which child elements are used to discriminate between the slices when processing an instance. If one or more discriminators are provided, the values 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.">discriminator Σ 0..* Element Element values that are used to distinguish the slices #xD; type Σ 1..1 code value | exists | type | profile | position Binding: DiscriminatorType (Required) #xD; path Σ 1..1 string Path to element value #xD; description ΣT 0..1 string Text description of how slicing works (or not) #xD; ordered ΣC 0..1 boolean If elements must be in same order as slices #xD; rules ΣC 1..1 code closed | open | openAtEnd Binding: SlicingRules (Required) #xD; short ΣT 0..1 string Concise definition for space-constrained presentation #xD; <a href="elementdefinition-definitions.html#ElementDefinition.definition" title="ElementDefinition.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).">definition ΣT 0..1 markdown Full formal definition as narrative text #xD; comment ΣT 0..1 markdown Comments about the use of this element #xD; requirements ΣT 0..1 markdown Requirements satisfied by this element/structure and its constraints #xD; alias ΣT 0..* string Other names #xD; min ΣC 0..1 unsignedInt Minimum Cardinality #xD; max ΣC 0..1 string Maximum Cardinality (a number or *) + Rule: Max SHALL be a number or "*" #xD; <a href="elementdefinition-definitions.html#ElementDefinition.base" title="ElementDefinition.base : 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 - e.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.">base Σ 0..1 Element Base definition information for tools #xD; path Σ 1..1 string Path that identifies the base element #xD; min Σ 1..1 unsignedInt Min cardinality of the base element #xD; max Σ 1..1 string Max cardinality of the base element #xD; <a href="elementdefinition-definitions.html#ElementDefinition.contentReference" title="ElementDefinition.contentReference : 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.">contentReference ΣC 0..1 uri Reference to definition of content for the element #xD; type ΣC 0..* Element Data type and Profile for this element + Rule: Aggregation may only be specified if one of the allowed types for the element is a reference + Rule: targetProfile is only allowed if the type is Reference or canonical + Warning: profiles SHOULD be unique + Warning: targetProfiles SHOULD be unique #xD; code ΣC 1..1 uri Data type or Resource (reference to definition) Binding: Element Definition Types (Extensible) #xD; <a href="elementdefinition-definitions.html#ElementDefinition.type.profile" title="ElementDefinition.type.profile : 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.">profile Σ 0..* canonical(StructureDefinition | ImplementationGuide) Profiles (StructureDefinition or IG) - one must apply #xD; <a href="elementdefinition-definitions.html#ElementDefinition.type.targetProfile" title="ElementDefinition.type.targetProfile : 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.">targetProfile ΣC 0..* canonical(StructureDefinition | ImplementationGuide) Profile (StructureDefinition or IG) on the Reference/canonical target - one must apply #xD; aggregation ΣC 0..* code contained | referenced | bundled - how aggregated Binding: AggregationMode (Required) #xD; versioning Σ 0..1 code either | independent | specific Binding: ReferenceVersionRules (Required) #xD; defaultValue[x] ΣC 0..1 * Specified value if missing from instance #xD; meaningWhenMissing ΣTC 0..1 markdown Implicit meaning when this element is missing #xD; orderMeaning ΣC 0..1 string What the order of the elements means #xD; fixed[x] ΣC 0..1 * Value must be exactly this #xD; <a href="elementdefinition-definitions.html#ElementDefinition.pattern_x_" title="ElementDefinition.pattern[x] : 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. #xA;#xA;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.#xA;#xA;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.#xA;#xA;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.,#xA;#xA;1. If primitive: it must match exactly the pattern value#xA;2. If a complex object: it must match (recursively) the pattern value#xA;3. If an array: it must match (recursively) the pattern value#xA;#xA;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](elementdefinition-examples.html#pattern-examples) for examples of pattern usage and the effect it will have.">pattern[x] ΣC 0..1 * Value must have at least these property values #xD; example ΣC 0..* Element Example value (as defined for type) #xD; label ΣT 1..1 string Describes the purpose of this example #xD; value[x] Σ 1..1 * Value of Example (one of allowed types) #xD; minValue[x] ΣC 0..1 Minimum Allowed Value (for some types) #xD; minValueDate date #xD; minValueDateTime dateTime #xD; minValueInstant instant #xD; minValueTime time #xD; minValueDecimal decimal #xD; minValueInteger integer #xD; minValueInteger64 integer64 #xD; 0)">minValuePositiveInt positiveInt #xD; = 0)">minValueUnsignedInt unsignedInt #xD; minValueQuantity Quantity #xD; maxValue[x] ΣC 0..1 Maximum Allowed Value (for some types) #xD; maxValueDate date #xD; maxValueDateTime dateTime #xD; maxValueInstant instant #xD; maxValueTime time #xD; maxValueDecimal decimal #xD; maxValueInteger integer #xD; maxValueInteger64 integer64 #xD; 0)">maxValuePositiveInt positiveInt #xD; = 0)">maxValueUnsignedInt unsignedInt #xD; maxValueQuantity Quantity #xD; <a href="elementdefinition-definitions.html#ElementDefinition.maxLength" title="ElementDefinition.maxLength : 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 have a length (see [Tupe Characteristics](datatypes.html#other) and [http://hl7.org/fhir/StructureDefinition/structuredefinition-type-characteristics]).">maxLength ΣC 0..1 integer Max length for string type data #xD; condition Σ 0..* id Reference to invariant about presence #xD; constraint ΣC 0..* Element Condition that must evaluate to true + Warning: Constraints should have an expression or else validators will not be able to enforce them + Rule: Errors cannot be suppressed #xD; key ΣC 1..1 id Target of 'condition' reference above #xD; requirements Σ 0..1 markdown Why this constraint is necessary or appropriate #xD; severity ΣC 1..1 code error | warning Binding: ConstraintSeverity (Required) #xD; suppress ΣC 0..1 boolean Suppress warning or hint in profile #xD; human ΣT 1..1 string Human description of constraint #xD; expression ΣC 0..1 string FHIRPath expression of constraint #xD; source Σ 0..1 canonical(StructureDefinition) Reference to original source of constraint #xD; mustHaveValue ΣC 0..1 boolean For primitives, that a value must be present - not replaced by an extension #xD; valueAlternatives ΣC 0..* canonical(StructureDefinition) Extensions that are allowed to replace a primitive value #xD; <a href="elementdefinition-definitions.html#ElementDefinition.mustSupport" title="ElementDefinition.mustSupport : If true, implementations that produce or consume resources SHALL provide "support" for the element in some meaningful way. Note that this is being phased out and replaced by obligations (see below). 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.">mustSupport Σ 0..1 boolean If the element must be supported (discouraged - see obligations) #xD; <a href="elementdefinition-definitions.html#ElementDefinition.isModifier" title="ElementDefinition.isModifier : 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. When used on the root element in an extension definition, this indicates whether or not the extension is a modifier extension.">isModifier ΣC 0..1 boolean If this modifies the meaning of other elements #xD; isModifierReason ΣC 0..1 string Reason that this element is marked as a modifier #xD; isSummary Σ 0..1 boolean Include when _summary = true? #xD; binding ΣC 0..1 Element ValueSet details if this is coded + Rule: ValueSet SHALL start with http:// or https:// or urn: or # + Rule: binding SHALL have either description or valueSet + Rule: If the strength is 'descriptive' no value set can ve provided + Guideline: if there's a required binding with no usage, it should be the base binding #xD; strength Σ 1..1 code required | extensible | preferred | example | descriptive Binding: BindingStrength (Required) #xD; description ΣTC 0..1 markdown Guidance on the codes to be used #xD; valueSet ΣC 0..1 canonical(ValueSet) Source of value set #xD; additional ΣC 0..* Element Additional Bindings - more rules about the binding + Guideline: additionalBindings should have a key #xD; key Σ 0..1 id Unique identifier so additional bindings to be matched across profiles #xD; purpose Σ 1..1 code maximum | minimum | required | extensible | candidate | current | current-extensible | best-practice | preferred | ui | starter | component Binding: Additional Binding Purpose ValueSet (Required) #xD; valueSet Σ 1..1 canonical(ValueSet) The value set for the additional binding #xD; documentation Σ 0..1 markdown Documentation of the purpose of use of the binding #xD; shortDoco Σ 0..1 string Concise documentation - for summary tables #xD; <a href="elementdefinition-definitions.html#ElementDefinition.binding.additional.usage" title="ElementDefinition.binding.additional.usage : Qualifies the usage of the binding. Typically bindings are qualified by jurisdiction, but they may also be qualified by gender, workflow status, clinical domain etc. The information to decide whether a usage context applies is usually outside the resource, determined by context, and this might present challenges for validation tooling.">usage Σ 0..* UsageContext Qualifies the usage - jurisdiction, gender, workflow status etc. #xD; any Σ 0..1 boolean Whether binding can applies to all repeats, or just one #xD; mapping ΣC 0..* Element Map element to another set of definitions #xD; identity ΣC 1..1 id Reference to mapping declaration #xD; language Σ 0..1 code Computable language of mapping Binding: Mime Types (Required) #xD; map Σ 1..1 string Details of the mapping #xD; comment Σ 0..1 markdown Comments about the mapping or its use #xD; Documentation for this format
ElementDefinition Type: Captures constraints on each element within the resource, profile, or extension.
Definition of an element in a resource or extension
Captures constraints on each element within the resource, profile, or extension.
min.empty() or max.empty() or (max = '*') or iif(max != '*', min <= max.toInteger())
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())
Fixed value may only be specified if there is one type
Pattern may only be specified if there is one type
Pattern and fixed are mutually exclusive
Binding can only be present for coded elements, string, and uri if using FHIR-defined types
binding.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()
default value and meaningWhenMissing are mutually exclusive
defaultValue.empty() or meaningWhenMissing.empty()
sliceName must be composed of proper tokens separated by "/"
sliceName.empty() or sliceName.matches('^[a-zA-Z0-9\\/\\-_\\[\\]\\@]+$')
Must have a modifier reason if isModifier = true
(isModifier.exists() and isModifier) implies isModifierReason.exists()
Element path SHALL be expressed as a set of '.'-separated components with each component restricted to a maximum of 64 characters and with some limits on the allowed choice of characters
The first component of the path should be UpperCamelCase. Additional components (following a '.') should be lowerCamelCase. If this syntax is not adhered to, code generation tools may be broken. Logical models may be less concerned about this implication.
sliceIsConstraining can only appear if slicename is present
sliceIsConstraining.exists() implies sliceName.exists()
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
pattern[x] should be used rather than fixed[x]
Order has no meaning (and cannot be asserted to have meaning), so enforcing rules on order is improper
orderMeaning.empty() implies slicing.where(rules='openAtEnd' or ordered).exists().not()
Can't have valueAlternatives if mustHaveValue is true
mustHaveValue.value implies valueAlternatives.empty()
If there's more than one bindable type, it's usually an error for there to be a binding
type.where(code in 'code' | 'Coding' | 'CodeableConcept' | 'CodeableReference' | 'uri' | 'string' | 'Quantity').count() > 1 implies binding.empty()
All FHIR elements must have a @value or children
hasValue() or (children().count() > id.count())
n/a,Observation[classCode=OBS, moodCode=DEFN]
Unique id for the element within a resource (for internal references). This may be any string value that does not contain spaces.
Extensions are always sliced by (at least) url
Additional content defined by implementations
May be used to represent additional information that is not part of the basic definition of the element. To make the use of extensions safe and managable, there is a strict set of governance applied to the definition and use of extensions. Though any implementer can define an extension, there is a set of requirements that SHALL be met as part of the definition of the extension.
There can be no stigma associated with the use of extensions by any application, project, or standard - regardless of the institution or jurisdiction that uses or defines the extensions. The use of extensions is what allows the FHIR specification to retain a core level of simplicity for everyone.
Extensions that cannot be ignored even if unrecognized
May be used to represent additional information that is not part of the basic definition of the element and that modifies the understanding of the element in which it is contained and/or the understanding of the containing element's descendants. Usually modifier elements provide negation or qualification. To make the use of extensions safe and managable, there is a strict set of governance applied to the definition and use of extensions. Though any implementer can define an extension, there is a set of requirements that SHALL be met as part of the definition of the extension. Applications processing a resource are required to check for modifier extensions. Modifier extensions SHALL NOT change the meaning of any elements on Resource or DomainResource (including cannot change the meaning of modifierExtension itself).
Modifier extensions allow for extensions that *cannot* be safely ignored to be clearly distinguished from the vast majority of extensions which can be safely ignored. This promotes interoperability by eliminating the need for implementers to prohibit the presence of extensions. For further information, see the [definition of modifier extensions](extensibility.html#modifierExtension).
Modifier extensions are expected to modify the meaning or interpretation of the element that contains them
Path of the element in the hierarchy of elements
The path identifies the element and is expressed as a "."-separated list of ancestor elements, beginning with the name of the resource or extension.
xmlAttr | xmlText | typeAttr | cdaText | xhtml
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.
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.).
How a property is represented when serialized.
Name for this particular element (in a set of slices)
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.
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.).
May also be used for code generation purposes.
If this slice definition constrains an inherited slice definition (or not)
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.
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.
Allows detection of a situation where an ancestor profile adds or removes slicing with the same name where that might impact the child profile.
String to display with or prompt for element
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.
See also the extension [Question](https://build.fhir.org/ig/HL7/fhir-extensions/StructureDefinition-elementdefinition-question.html).
A code that has the same meaning as the element in a particular terminology.
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. This is used for both mapping to formal terminologies as well as to informal collections of data elements provided they can be treated as a 'system' (i.e. a single namespace with a canonical URI). For mappings to more complex structures not identifiable with a single id, use the ElementDefinition.mapping structure.
Links the meaning of an element to an external terminology, and is very useful for searching and indexing.
Codes that indicate the meaning of a data element.
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).
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.
All FHIR elements must have a @value or children or both
Element values that are used to distinguish the slices
Designates which child elements are used to discriminate between the slices when processing an instance. If one or more discriminators are provided, the values 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.
If there is no discriminator, the content is hard to process, so this should be avoided.
value | exists | type | profile | position
How the element value is interpreted when discrimination is evaluated.
'pattern' is deprecated - it works exactly the same as 'value'.
How an element value is interpreted when discrimination is evaluated.
A FHIRPath expression, using [the simple subset of FHIRPath](fhirpath.html#simple), that is used to identify the element on which discrimination is based.
Text description of how slicing works (or not)
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.
If it's really not possible to differentiate them, the design should be re-evaluated to make the content usable.
If elements must be in same order as slices
If the matching elements have to occur in the same order as defined in the profile.
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.
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.
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.
How slices are interpreted when evaluating an instance.
Concise definition for space-constrained presentation
A concise description of what this element means (e.g. for use in autogenerated summaries).
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.
Full formal definition as narrative text
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).
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.
To allow a user to state the usage of an element in a particular context.
(Designatable_Item).definition.text acceptability=preferred in default context
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).
If it is possible to capture usage rules using constraints, that mechanism should be used in preference to this element.
./inboundRelationship[typeCode=SUBJ]/source[classCode=LIST, moodCode=EVN]/code
Requirements satisfied by this element/structure and its constraints
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.
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.
./inboundRelationship[typeCode=META]/source[classCode=ACT, moodCode=EVN, isCriterionInd=true]/reasonCode/originalText
Identifies additional names by which this element might also be known.
Allows for better easier recognition of the element by multiple communities, including international communities.
(Designatable_Item).designation.sign acceptability!=preferred or context is other than default
The minimum number of times this element SHALL appear in the instance.
The maximum number of times this element is permitted to appear in the instance.
empty() or ($this = '*') or (toInteger() >= 0)
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 - e.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.
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.
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](structuredefinition.html#) without a StructureDefinition.base.
Minimum cardinality of the base element identified by the path.
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).
Maximum cardinality of the base element identified by the path.
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.
Reference to definition of content for the element
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.
ContentReferences can only be defined in specializations, not constrained types, and they cannot be changed and always reference the non-constrained definition.
The data type or resource that the value of this element is permitted to be.
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).
Aggregation may only be specified if one of the allowed types for the element is a reference
aggregation.empty() or (code = 'Reference') or (code = 'canonical') or (code = 'CodeableReference')
targetProfile is only allowed if the type is Reference or canonical
(code='Reference' or code = 'canonical' or code = 'CodeableReference') or targetProfile.empty()
Data type or Resource (reference to 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.
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).
List of all Types for ElementDefinition.type.code.
Profiles (StructureDefinition or IG) - one must apply
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.
It is possible to profile backbone element (e.g. part of a resource), using the [Profile Element](https://build.fhir.org/ig/HL7/fhir-extensions/StructureDefinition-elementdefinition-profile-element.html) extension.
Profile (StructureDefinition or IG) on the Reference/canonical target - one must apply
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.
contained | referenced | bundled - how aggregated
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.
See [Aggregation Rules](elementdefinition.html#aggregation) for further clarification.
How resource references can be aggregated.
Whether this reference needs to be version specific or version independent, or whether either can be used.
The base specification never makes a rule as to which form is allowed, but implementation guides may do this. See [Aggregation Rules](elementdefinition.html#aggregation) for further clarification.
Whether a reference needs to be version specific or version independent, or whether either can be used.
Specified value if missing from instance
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').
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.
Implicit meaning when this element is missing
The Implicit meaning that is to be understood when this element is missing (e.g. 'when this element is missing, the period is ongoing').
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.
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.
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.
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.
This is not recommended for Coding and CodeableConcept since these often have highly contextual properties such as version or display.
N/A (only relevant when constraining, which 11179 doesn't do)
Value must have at least these property values
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](elementdefinition-examples.html#pattern-examples) for examples of pattern usage and the effect it will have.
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].
A sample value for this element demonstrating the type of information that would typically be found in the element.
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.
Describes the purpose of this example among the set of examples.
The actual value for the element, which must be one of the types allowed for this element.
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.
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](datatypes.html#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 a canonical minimum - e.g. you cannot provide 100mg if the minimum value is 10g.
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.
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](datatypes.html#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 a canonical maximum - e.g. you cannot provide 10g if the maximum value is 50mg.
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 have a length (see [Tupe Characteristics](datatypes.html#other) and [Structure Type Characterstics (Constraint Control)](https://build.fhir.org/ig/HL7/fhir-extensions/StructureDefinition-structuredefinition-type-characteristics.html)).
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.
A reference to an invariant that may make additional statements about the cardinality or value in the instance.
Formal constraints such as co-occurrence and other constraints that can be computationally evaluated within the context of the instance.
Constraints should be declared on the "context" element - the lowest element in the hierarchy that is common to all nodes referenced by the constraint.
Constraints should have an expression or else validators will not be able to enforce them
(severity = 'error') implies suppress.empty()
Allows identification of which elements have their cardinalities impacted by the constraint. Will not be referenced for constraints that do not affect cardinality.
Why this constraint is necessary or appropriate
Description of why this constraint is necessary or appropriate.
To be used if the reason for the constraint might not be intuitive to all implementers.
Identifies the impact constraint violation has on the conformance of the instance.
This allows constraints to be asserted as "shall" (error) and "should" (warning).
SHALL applications comply with this constraint?
If true, indicates that the warning or best practice guideline should be suppressed.
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.
Text that can be used to describe the constraint in messages identifying that the constraint has been violated.
Should be expressed in business terms as much as possible.
A [FHIRPath](fhirpath.html) expression of constraint that can be executed to see if this constraint is met.
In the absense of an expression, the expression is likely not enforceable by validators, and might be missed by many systems.
Used by validation tooling tests of the validity of the resource.
Reference to original source of constraint
A reference to the original source of the constraint, for traceability purposes.
This is used when it is not useful to present inherited constraints while rendering the snapshot.
For primitives, that a value must be present - not replaced by an extension
Specifies for a primitive data type that the value of the data type cannot be replaced by an extension.
Typical extensions that can be provided in place of a the value are [Data Absent Reason](https://build.fhir.org/ig/HL7/fhir-extensions/StructureDefinition-data-absent-reason.html), [Null flavor](https://build.fhir.org/ig/HL7/fhir-extensions/StructureDefinition-iso21090-nullFlavor.html), [Original Text](https://build.fhir.org/ig/HL7/fhir-extensions/StructureDefinition-originalText.html), and [CQF Expression](https://build.fhir.org/ig/HL7/fhir-extensions/StructureDefinition-cqf-expression.html). Note that this element has no meaning when a value is provided, and extensions can be provided in addition to a value.
Extensions that are allowed to replace a primitive value
Specifies a list of extensions that can appear in place of a primitive value.
If mustHaveValue is true, then this element should not be present, since no extensions are allowed in place of the value. Note that this element has no impact if the value is present. When valueAlternatives is present, it means that if the element is present, it SHALL have either a value or at least one of the listed extensions. This element is only permitted on elements with primitive types.
If this element is missing, then any extension can be used if its context is appropriate
If the element must be supported (discouraged - see obligations)
If true, implementations that produce or consume resources SHALL provide "support" for the element in some meaningful way. Note that this is being phased out and replaced by obligations (see below). 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.
"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](profiling.html#mustsupport), 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.
Allows a profile to set expectations for system capabilities beyond merely respecting cardinality constraints.
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 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
If this modifies the meaning of other elements
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. When used on the root element in an extension definition, this indicates whether or not the extension is a modifier extension.
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 (except in the special case of the defining a new extension). 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. See further discussion in the [conformance rules](conformance-rules.html#isModifier) section.
Allows elements to be introduced into a specification that can't safely be ignored by applications that don't recognize them.
An element is not a modifier element unless it is explicitly specified to be one
Reason that this element is marked as a modifier
Explains how that element affects the interpretation of the resource or element that contains it.
Whether the element should be included if a client requests a search with the parameter _summary=true.
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 within the same StructureDefinition 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.
Allow clients to search through large resources quickly.
An element is not included in the summary unless it is explicitly specified to be so
Binds to a value set if this element is coded (code, Coding, CodeableConcept, Quantity), or the data types (string, uri).
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.
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('#'))
binding SHALL have either description or valueSet
description.exists() or valueSet.exists()
If the strength is 'descriptive' no value set can ve provided
strength = 'descriptive' implies valueSet.empty()
Authors are encouraged to but the max value set on the root, and provide other additional value sets as additional bindings
if there's a required binding with no usage, it should be the base binding
strength != 'required' implies additional.where(purpose = 'required' and usage.empty()).empty()
required | extensible | preferred | example | descriptive
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.
For further discussion, see [Using Terminologies](terminologies.html).
Indication of the degree of conformance expectations associated with a binding.
Free-text guidance on the codes that are appropriate for this element.
This may provide an ad-hoc description of the expected/desired codes in situations where defining a specific value set is not possible, to provide additional context to a value set that is provided, or to give a summary where terminology constraints are expressed only as additional bindings.
Refers to the value set that identifies the set of codes the binding refers to.
The reference may be version-specific or not (e.g. have a |[version] at the end of the canonical URL).
points to explicit list or expression that evaluates to list of (Enumerated_Value_Domain).member
Additional Bindings - more rules about the binding
Additional bindings that help applications implementing this element. Additional bindings do not replace the main binding but provide more information and/or context.
If there are multiple additional bindings, they all apply independently of each other.
AdditionalBinding.key is necessary to allow a binding to be constrained
Unique identifier so additional bindings to be matched across profiles
A unique identifier for the additional binding within the element that allows additional bindings to be matched across profiles.
maximum | minimum | required | extensible | candidate | current | current-extensible | best-practice | preferred | ui | starter | component
Conformance bindings are in addition to the base binding, not instead of it.
The value set for the additional binding
The valueSet that is being bound for the purpose.
Documentation of the purpose of use of the binding
Documentation of the purpose of use of the binding, providing additional information about how it is intended to be used.
Concise documentation - for summary tables
Concise documentation - for summary tables.
Qualifies the usage - jurisdiction, gender, workflow status etc.
Qualifies the usage of the binding. Typically bindings are qualified by jurisdiction, but they may also be qualified by gender, workflow status, clinical domain etc. The information to decide whether a usage context applies is usually outside the resource, determined by context, and this might present challenges for validation tooling.
This specification does not define exactly how the context is determined for the usage; typically, this will be described in implementation guides.
Whether binding can applies to all repeats, or just one
Whether the binding applies to all repeats, or just to any one of them. This is only relevant for elements that can repeat.
A common pattern is to make a conformance binding to all repeats, and then make a binding that one of the repeats must conform to.
Map element to another set of definitions
Identifies a concept from an external specification that roughly corresponds to this element.
Mappings are not necessarily specific enough for safe translation. Note that ElementDefinition.code can provide a mapping to terminologies or other simple data element collections.
Provides guidance to implementers familiar with or converting content from other specifications.
Registered_item).document_reference[document_type=mapping] Also, .meaning linkage to Data_Element_Concept is done as a mapping to a reference model. (Data_Element_Concepts are all defined in some sort of reference model, be that Object_Class and Property or some other mechanism)
An internal reference to the definition of a mapping.
Identifies the computable language in which mapping.map is expressed.
If omitted, then there can be no expectation of computational interpretation of the mapping.
The mime type of an attachment. Any valid mime type is allowed.
Expresses what part of the target specification corresponds to this element.
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.
ObjectClass, Property (this is one possible data model that can be mapped to - the uri would identify the data model mappingSpecification.mappingScript
Comments that provide information about the mapping or its use.
Observation[classCode=OBS, moodCode=DEFN]