Complex
Primitive
ActivityDefinition
CapabilityStatement
CodeSystem
Composition
ConceptMap
Encounter
Library
List
Measure
MessageHeader
Observation
Patient
PlanDefinition
Questionnaire
Resource
ServiceDefinition
StructureDefinition
StructureMap
ValueSet
default
A fixed quantity (no comparator)
Quantity
Path
Quantity:simplequantity
Id
Quantity:simplequantity
Cardinality
0 - *
Definition
The comparator is not used on a SimpleQuantity
Comment
The context of use may frequently define what kind of quantity this is and therefore what kind of units can be used. The context of use may also restrict the values for the comparator.
Constraint
ele-1 [error]
All FHIR elements must have a @value or children
qty-3 [error]
If a code for the unit is present, the system SHALL also be present
sqty-1 [error]
The comparator is not used on a SimpleQuantity
Condition
ele-1
Path
Quantity:simplequantity.value
Id
Quantity:simplequantity.value
Type
Cardinality
0 - 1
Definition
The value of the measured amount. The value includes an implicit precision in the presentation of the value.
Comment
The implicit precision in the value should always be honored. Monetary values have their own rules for handling precision (refer to standard accounting text books).
Requirements
Precision is handled implicitly in almost all cases of measurement.
Path
Quantity:simplequantity.comparator
Id
Quantity:simplequantity.comparator
Type
Cardinality
0 - 0
Definition
Not allowed to be used in this context
Comment
This is labeled as "Is Modifier" because the comparator modifies the interpretation of the value significantly. If there is no comparator, then there is no modification of the value.
Requirements
Need a framework for handling measures where the value is <5ug/L or >400mg/L due to the limitations of measuring methodology.
Path
Quantity:simplequantity.unit
Id
Quantity:simplequantity.unit
Type
Cardinality
0 - 1
Definition
A human-readable form of the unit.
Comment
Requirements
There are many representations for units of measure and in many contexts, particular representations are fixed and required. I.e. mcg for micrograms.
Path
Quantity:simplequantity.system
Id
Quantity:simplequantity.system
Type
Cardinality
0 - 1
Definition
The identification of the system that provides the coded form of the unit.
Comment
Requirements
Need to know the system that defines the coded form of the unit.
Condition
qty-3
Path
Quantity:simplequantity.code
Id
Quantity:simplequantity.code
Type
Cardinality
0 - 1
Definition
A computer processable form of the unit in some unit representation system.
Comment
The preferred system is UCUM, but SNOMED CT can also be used (for customary units) or ISO 4217 for currency. The context of use may additionally require a code from a particular system.
Requirements
Need a computable form of the unit that is fixed across all forms. UCUM provides this for quantities, but SNOMED CT provides many units of interest.