http://hl7.org/fhir/StructureDefinition/extension-quantity-translation|5.2.0

An alternative representation of the same physical quantity expressed in a different unit from a different unit code system and possibly with a different value.
NameFlagsCardTypeDescription & Constraints
Extension
0..*Same quantity with different units
 
extension
?..0
 
url
?..?
 
value[x] *
1..?
 
 
valueQuantity *
1..?Quantity