The Age element allows the age of the subject to be encoded in several different ways that support different use cases. Age is encoded as ISO8601 duration.

Data model

Field Type Multiplicity Description
iso8601duration string 1..1 An ISO8601 string represent age

If the Age message is used, the iso8601duration value must be present.


  iso8601duration: "P25Y3M2D"

The string element (string age=1) should be used for ISO8601 durations (e.g., P40Y10M05D). For many use cases, less precise strings will be preferred for privacy reasons, e.g., P40Y.


It is possible to represent age using a string that should be formatted according to ISO8601 Duration.


The AgeRange element is intended to be used when the age of a subject is represented by a bin, e.g., 5-10 years. Bins such as this are used in some situations in order to protect the privacy of study participants, whose age is then represented by bins such as 45-49 years, 50-54 years, 55-59 years, and so on.

Data model

Field Type Multiplicity Description
start Age 1..1 An Age message
end Age 1..1 An Age message


For instance, to represent the bin 45-49 years, one could use an Age element with P45Y as the start element of the AgeRange element, and an Age element with P49Y as the end element. An AgeRange.end SHALL occur after AgeRange.start.

      iso8601duration: "P45Y"
      iso8601duration: "P49Y"