Extension 
url 
value[x] Binding: ?? (required)
valueCodeableConcept
valueCanonical Documentation for this formatThis is the set of resources that conform to either of the profiles Allowed Units (http://hl7.org/fhir/StructureDefinition/elementdefinition-allowedUnits) and Allowed Units (http://hl7.org/fhir/StructureDefinition/elementdefinition-allowedUnits). E.g. what you have to deal with if you get resources conforming to one of them
| Name | Flags | Card. | Type | Description & Constraints Filter: |
|---|---|---|---|---|
| Extension | 0..1 | Units to use for measured value | ||
| url | 1..1 | uri | identifies the meaning of the extension | |
| value[x] | 1..1 | Value of extension Binding: ?? (required) | ||
| valueCodeableConcept | CodeableConcept | |||
| valueCanonical | canonical(ValueSet) | |||
| Documentation for this format | ||||