1.13.2.0 Element Definition
Introduction
1.13.2.0.1
Content
Structure UML
XML JSON
All
Min <= Max
Pattern may only be specified if there is one type
Fixed value may only be specified if there is one type
Either a namereference or a fixed value (but not both) is permitted
Constraint names must be unique.
Pattern and value are mutually exclusive
default value and meaningWhenMissing are mutually exclusive
Types must be unique by the combination of code and profile
Constraints must be unique by key
Binding can only be present for coded elements
PropertyRepresentation (Required)
If there is no discriminators, there must be a description
SlicingRules (Required)
Max SHALL be a number or ""
Aggregation may only be specified if one of the allowed types for the element is a resource
DataType (Required)
AggregationMode (Required)
ConstraintSeverity (Required)
provide either a reference or a description (or both)
Example value sets are always extensible
BindingConformance (Required)
uri SHALL start with http:// or https://
UML Diagram
to do
XML Template
<[name] xmlns="http://hl7.org/fhir">
<!– from Element: extension –>
<path value="[string]"/><!– 1..1 The path of the element (see the Detailed Descriptions) –>
<representation value="[code]"/><!– 0..* How this element is represented in instances –>
<name value="[string]"/><!– 0..1 Name for this particular element definition (reference target) –>
<slicing> <!– 0..1 This element is sliced - slices follow –>
<discriminator value="[string]"/><!– 0..* Element values that used to distinguish the slices –>
<description value="[string]"/><!– 0..1 Text description of how slicing works (or not) –>
<ordered value="[boolean]"/><!– 0..1 If elements must be in same order as slices –>
<rules value="[code]"/><!– 1..1 closed | open | openAtEnd –>
</slicing>
<short value="[string]"/><!– 0..1 Concise definition for xml presentation –>
<formal value="[string]"/><!– 0..1 Full formal definition in human language –>
<comments value="[string]"/><!– 0..1 Comments about the use of this element –>
<requirements value="[string]"/><!– 0..1 Why is this needed? –>
<synonym value="[string]"/><!– 0..* Other names –>
<min value="[integer]"/><!– 0..1 Minimum Cardinality –>
<max value="[string]"/><!– 0..1 Maximum Cardinality (a number or ) –>
<type> <!– 0.. Data type and Profile for this element –>
<code value="[code]"/><!– 1..1 Name of Data type or Resource –>
<profile value="[uri]"/><!– 0..1 Profile.structure to apply –>
<aggregation value="[code]"/><!– 0..* contained | referenced | bundled - how aggregated –>
</type>
<nameReference value="[string]"/><!– 0..1 To another element constraint (by element.name) –>
<defaultValue[x]><!– 0..1 * Specified value it missing from instance –></defaultValue[x]>
<meaningWhenMissing value="[string]"/><!– 0..1 Implicit meaning when this element is missing –>
<fixed[x]><!– 0..1 * Value must be exactly this –></fixed[x]>
<pattern[x]><!– 0..1 * Value must have at least these property values –></pattern[x]>
<example[x]><!– 0..1 * Example value: [as defined for type] –></example[x]>
<maxLength value="[integer]"/><!– 0..1 Max length for strings –>
<condition value="[id]"/><!– 0..* Reference to invariant about presence –>
<constraint> <!– 0..* Condition that must evaluate to true –>
<key value="[id]"/><!– 1..1 Target of ‘condition’ reference above –>
<name value="[string]"/><!– 0..1 Short human label –>
<severity value="[code]"/><!– 1..1 error | warning –>
<human value="[string]"/><!– 1..1 Human description of constraint –>
<xpath value="[string]"/><!– 1..1 XPath expression of constraint –>
</constraint>
<mustSupport value="[boolean]"/><!– 0..1 If the element must supported –>
<isModifier value="[boolean]"/><!– 0..1 If this modifies the meaning of other elements –>
<isSummary value="[boolean]"/><!– 0..1 Include when _summary = true? –>
<binding> <!– 0..1 ValueSet details if this is coded –>
<name value="[string]"/><!– 1..1 Descriptive Name –>
<isExtensible value="[boolean]"/><!– 1..1 Can additional codes be used? –>
<conformance value="[code]"/><!– 0..1 required | preferred | example –>
<description value="[string]"/><!– 0..1 Human explanation of the value set –>
<reference[x]><!– 0..1 uri|Reference(ValueSet) Source of value set –></reference[x]>
</binding>
<mapping> <!– 0..* Map element to another set of definitions –>
<identity value="[id]"/><!– 1..1 Reference to mapping declaration –>
<map value="[string]"/><!– 1..1 Details of the mapping –>
</mapping>
</[name]>
JSON Template
todo
Structure
Name | Flags | Card. | Type | Description & Constraints |
---|---|---|---|---|
ElementDefinition | I | 0.. | Element | Definition of an elements in a resource or extension Min <= Max Pattern may only be specified if there is one type Fixed value may only be specified if there is one type Either a namereference or a fixed value (but not both) is permitted Constraint names must be unique. Pattern and value are mutually exclusive default value and meaningWhenMissing are mutually exclusive Types must be unique by the combination of code and profile Constraints must be unique by key Binding can only be present for coded elements |
path | 1..1 | string | The path of the element (see the Detailed Descriptions) | |
representation | 0.. | code | How this element is represented in instances PropertyRepresentation (Required) | |
name | 0..1 | string | Name for this particular element definition (reference target) | |
slicing | I | 0..1 | Element | This element is sliced - slices follow If there is no discriminators, there must be a description |
discriminator | 0.. | string | Element values that used to distinguish the slices | |
description | I | 0..1 | string | Text description of how slicing works (or not) |
ordered | 0..1 | boolean | If elements must be in same order as slices | |
rules | 1..1 | code | closed | open | openAtEnd SlicingRules (Required) | |
short | 0..1 | string | Concise definition for xml presentation | |
formal | 0..1 | string | Full formal definition in human language | |
comments | 0..1 | string | Comments about the use of this element | |
requirements | 0..1 | string | Why is this needed? | |
synonym | 0.. | string | Other names | |
min | I | 0..1 | integer | Minimum Cardinality |
max | I | 0..1 | string | Maximum Cardinality (a number or ) Max SHALL be a number or "" |
type | I | 0.. | Element | Data type and Profile for this element Aggregation may only be specified if one of the allowed types for the element is a resource |
code | 1..1 | code | Name of Data type or Resource DataType (Required) | |
profile | 0..1 | uri | Profile.structure to apply | |
aggregation | I | 0.. | code | contained | referenced | bundled - how aggregated AggregationMode (Required) |
nameReference | I | 0..1 | string | To another element constraint (by element.name) |
defaultValue[x] | I | 0..1 | * | Specified value it missing from instance |
meaningWhenMissing | I | 0..1 | string | Implicit meaning when this element is missing |
fixed[x] | I | 0..1 | * | Value must be exactly this |
pattern[x] | I | 0..1 | * | Value must have at least these property values |
example[x] | 0..1 | * | Example value: [as defined for type] | |
maxLength | 0..1 | integer | Max length for strings | |
condition | 0.. | id | Reference to invariant about presence | |
constraint | 0.. | Element | Condition that must evaluate to true | |
key | I | 1..1 | id | Target of ‘condition’ reference above |
name | I | 0..1 | string | Short human label |
severity | 1..1 | code | error | warning ConstraintSeverity (Required) | |
human | 1..1 | string | Human description of constraint | |
xpath | 1..1 | string | XPath expression of constraint | |
mustSupport | 0..1 | boolean | If the element must supported | |
isModifier | 0..1 | boolean | If this modifies the meaning of other elements | |
isSummary | 0..1 | boolean | Include when _summary = true? | |
binding | I | 0..1 | Element | ValueSet details if this is coded provide either a reference or a description (or both) Example value sets are always extensible |
name | 1..1 | string | Descriptive Name | |
isExtensible | I | 1..1 | boolean | Can additional codes be used? |
conformance | I | 0..1 | code | required | preferred | example BindingConformance (Required) |
description | I | 0..1 | string | Human explanation of the value set |
reference[x] | I | Source of value set uri SHALL start with http:// or https:// | ||
referenceUri | 0..1 | uri | ||
referenceReference | 0..1 | ValueSet | ||
mapping | 0..* | Element | Map element to another set of definitions | |
identity | 1..1 | id | Reference to mapping declaration | |
map | 1..1 | string | Details of the mapping |
XML Template
<[name] xmlns="http://hl7.org/fhir">
<!– from Element: extension –>
<path value="[string]"/><!– 1..1 The path of the element (see the Detailed Descriptions) –>
<representation value="[code]"/><!– 0..* How this element is represented in instances –>
<name value="[string]"/><!– 0..1 Name for this particular element definition (reference target) –>
<slicing> <!– 0..1 This element is sliced - slices follow –>
<discriminator value="[string]"/><!– 0..* Element values that used to distinguish the slices –>
<description value="[string]"/><!– 0..1 Text description of how slicing works (or not) –>
<ordered value="[boolean]"/><!– 0..1 If elements must be in same order as slices –>
<rules value="[code]"/><!– 1..1 closed | open | openAtEnd –>
</slicing>
<short value="[string]"/><!– 0..1 Concise definition for xml presentation –>
<formal value="[string]"/><!– 0..1 Full formal definition in human language –>
<comments value="[string]"/><!– 0..1 Comments about the use of this element –>
<requirements value="[string]"/><!– 0..1 Why is this needed? –>
<synonym value="[string]"/><!– 0..* Other names –>
<min value="[integer]"/><!– 0..1 Minimum Cardinality –>
<max value="[string]"/><!– 0..1 Maximum Cardinality (a number or ) –>
<type> <!– 0.. Data type and Profile for this element –>
<code value="[code]"/><!– 1..1 Name of Data type or Resource –>
<profile value="[uri]"/><!– 0..1 Profile.structure to apply –>
<aggregation value="[code]"/><!– 0..* contained | referenced | bundled - how aggregated –>
</type>
<nameReference value="[string]"/><!– 0..1 To another element constraint (by element.name) –>
<defaultValue[x]><!– 0..1 * Specified value it missing from instance –></defaultValue[x]>
<meaningWhenMissing value="[string]"/><!– 0..1 Implicit meaning when this element is missing –>
<fixed[x]><!– 0..1 * Value must be exactly this –></fixed[x]>
<pattern[x]><!– 0..1 * Value must have at least these property values –></pattern[x]>
<example[x]><!– 0..1 * Example value: [as defined for type] –></example[x]>
<maxLength value="[integer]"/><!– 0..1 Max length for strings –>
<condition value="[id]"/><!– 0..* Reference to invariant about presence –>
<constraint> <!– 0..* Condition that must evaluate to true –>
<key value="[id]"/><!– 1..1 Target of ‘condition’ reference above –>
<name value="[string]"/><!– 0..1 Short human label –>
<severity value="[code]"/><!– 1..1 error | warning –>
<human value="[string]"/><!– 1..1 Human description of constraint –>
<xpath value="[string]"/><!– 1..1 XPath expression of constraint –>
</constraint>
<mustSupport value="[boolean]"/><!– 0..1 If the element must supported –>
<isModifier value="[boolean]"/><!– 0..1 If this modifies the meaning of other elements –>
<isSummary value="[boolean]"/><!– 0..1 Include when _summary = true? –>
<binding> <!– 0..1 ValueSet details if this is coded –>
<name value="[string]"/><!– 1..1 Descriptive Name –>
<isExtensible value="[boolean]"/><!– 1..1 Can additional codes be used? –>
<conformance value="[code]"/><!– 0..1 required | preferred | example –>
<description value="[string]"/><!– 0..1 Human explanation of the value set –>
<reference[x]><!– 0..1 uri|Reference(ValueSet) Source of value set –></reference[x]>
</binding>
<mapping> <!– 0..* Map element to another set of definitions –>
<identity value="[id]"/><!– 1..1 Reference to mapping declaration –>
<map value="[string]"/><!– 1..1 Details of the mapping –>
</mapping>
</[name]>
Commentary
Constraints
Inv-2: Min <= Max (xpath: (f:max/@value = ‘‘) or (f:max/@value >= f:min/@value))
Inv-5: Either a namereference or a fixed value (but not both) is permitted (xpath: not(exists(f:nameReference) and exists(f:[starts-with(local-name(.), ‘value’)])))
Inv-6: Fixed value may only be specified if there is one type (xpath: not(exists(f:[starts-with(local-name(.), ‘fixed’)])) or (count(f:type)=1 ))
Inv-7: Pattern may only be specified if there is one type (xpath: not(exists(f:[starts-with(local-name(.), ‘pattern’)])) or (count(f:type)=1 ))
Inv-8: Pattern and value are mutually exclusive (xpath: not(exists(f:[starts-with(local-name(.), ‘pattern’)])) or not(exists(f:[starts-with(local-name(.), ‘value’)]))) Inv-11: Binding can only be present for coded elements (xpath: not(exists(f:binding)) or (count(f:type/f:code) = 0) or f:type/f:code/@value=(‘code’,’Coding’,’CodeableConcept’,’Quantity’,’Extension’))
Inv-13: Types must be unique by the combination of code and profile (xpath: not(exists(for $type in f:type return $type/preceding-sibling::f:type[f:code/@value=$type/f:code/@value and f:profile/@value = $type/f:profile/@value]))) Inv-14: Constraints must be unique by key (xpath: count(f:constraint) = count(distinct-values(f:constraint/f:key/@value)))
Inv-15: Constraint names must be unique. (xpath: count(f:constraint[f:name]) = count(distinct-values(f:constraint/f:name/@value))) Inv-16: default value and meaningWhenMissing are mutually exclusive (xpath: not(exists(f:[starts-with(local-name(.), ‘fixed’)])) or not(exists(f:meaningWhenMissing))) Inv-1: On ElementDefinition.slicing: If there is no discriminators, there must be a description (xpath on f:ElementDefinition/f:slicing: (f:discriminator) or (f:description))
Inv-3: On ElementDefinition.max: Max SHALL be a number or "" (xpath on f:ElementDefinition/f:max: @value=’‘ or (normalize-space(@value)!=’’ and normalize-space(translate(@value, ‘0123456789’,’’))=’’)) Inv-4: On ElementDefinition.type: Aggregation may only be specified if one of the allowed types for the element is a resource (xpath on f:ElementDefinition/f:type: not(exists(f:aggregation)) or exists(f:code[@value = ‘Reference’]))
Inv-9: On ElementDefinition.binding: Example value sets are always extensible (xpath on f:ElementDefinition/f:binding: not(f:conformance/@value=’example’ and f:isExtensible/@value=’false’)) Inv-10: On ElementDefinition.binding: provide either a reference or a description (or both) (xpath on f:ElementDefinition/f:binding: (exists(f:referenceUri) or exists(f:referenceResource)) or exists(f:description))
*Inv-12: On ElementDefinition.binding.reference[x]: uri SHALL start with http:// or https:// (xpath on f:ElementDefinition/f:binding/f:reference[x]: starts-with(@value, ‘http:’) or starts-with(@value, ‘https:’))
Further Commentary
1.13.2.0.2 Interpretation of ElementDefinition in different contexts
The pseudo-data type ElementDefinition
is used both in Profile and ExtensionDefinition, and even within those resources, the way its elements are to be used and interpreted depend on the context where ElementDefinition
used.
1.13.2.0.2.1 First (root) element in a Structure
- Must be a "complex" element (see below)
path
is equal to the name of the type indicated in Structure.typename
associates a name- Prohibited:
slicing
,nameReference
,fixed
,mustSupport
,isSummary
type
is set to "DomainResource" or (rarely) "Resource" for constraints on Resources, "Element" for constraints on data typespattern
indicates a value that an instance of a while complex type constrained by this structure must match. May be used instead of applying constraints to the nested elements of the data type.example
example value for a complex type in an instance that complies to the structuremin
andmax
are prohibited unless defining an extension, in which case they set outer bounds on how the element can appear when referenced in a profileisModifier
is prohibited when defining resources or data types. When defining extensions, this indicates whether the extension is a modifier extensionisSummary
is prohibited when defining resources or data types. When defining extensions, this indicates whether the extension is a modifier extension
1.13.2.0.2.2 Nested element in a structure
(i.e. not root)
slicing
can only be used on the first repeat of an element, this element is considered the slicing entry
1.13.2.0.2.3 Element in a structure acting as the slicing entry
The ElementDefinition
is understood to be the set of constraints to be used for the "open" slice, i.e. when the slice is open, this definition is used as a constraint on elements in the instance that are not part of a slice and belong to the open portion of the slice. Its use follows the "normal case", except:
slicing
must be presentmin
andmax
govern the number of total occurrences of the sliced element including the number of occurrences in the open portion of the slice.
1.13.2.0.2.4 Resource and Extension definitions
- Prohibited:
name
slicing
is only supported when slicing based on type (to assert different rules/guidance for resources with multiple types, e.g. "code|integer" or "Reference(Foo|Bar)"
1.13.2.0.2.5 Only element in a simple extension
path
is equal to ExtensionmustSupport
may be used, but if it is not present it defaults to "false"
1.13.2.0.2.6 First (root) element in a complex extension
path
is equal to Extensiontype
is set toExtension
1.13.2.0.2.7 Nested element in a complex extension
representation
may not be usedslicing
may be used to express constraints on the use of specific types when the element allows a choice of type (name ends in [x])
*mustSupport
may be used, but if it is not present it defaults to "false"isModifier
may be used, but if it is not present it defaults to "false"
1.13.2.0.2.8 Complex elements (elements with upper-case data type)
representation
is prohibited*
maxLength
may not be used
1.13.2.0.2.9 Additional constraints
binding
may only be used on elements which allow a type of code, Coding or CodeableConcept (this includes *)
1.13.2.0.2.10 Constraint rules
short
,formal
,comments
,requirements
,synonym
,mapping
can be replaced with content that provides more contextual guidance.However, the new text must still be aligned with the base element. I.e. An instance that is created based on the definition, usage notes, etc. of the profiled element must still also be valid
against the definition, usage notes, etc. of the base element.- Supplementary information may be appended to
comments
,requirements
andsynonym
- Additional
condition
,constraint
andmapping
elements may be added Mapping
elements can be removed if they do not apply within the new contextisModifier
andisSummary
must be the same as the base definition for the data type or Resource
ElementDefinition is used in the following places: Profile and ExtensionDefinition
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