Period

Base StructureDefinition for Period Type: A time period defined by a start and end date and optionally time.

Complex data type in FHIR R4. Maturity: Not stated.

Elements

Element	Type	Cardinality	Description
id	string	0..1	Unique id for inter-element referencing
extension	Extension	0..*	Additional content defined by implementations
start	dateTime	0..1	Starting time with inclusive boundary
end	dateTime	0..1	End time with inclusive boundary, if not ongoing

Reference

Official FHIR R4 specification: Period.