Path
Age
Id
Age
Cardinality
0 - *
Definition
A duration of time during which an organism (or a process) has existed.
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
There SHALL be a code if there is a value and it SHALL be an expression of time. If system is present, it SHALL be UCUM. If value is present, it SHALL be positive.
All FHIR elements must have a @value or children
If a code for the unit is present, the system SHALL also be present