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occurrenceDateTime: An activity that takes place once on a specified date and time.occurencePeriod: An activity that takes place once in a specified period.occurenceTiming: This is for recurring activities. For example, a measurement should be performed each Monday at 10:00.
The Timing structure can express recurrence in several different ways. There are no hard restrictions on how fields Apart from constraints in place for Timing (see https://hl7.org/fhir/R4/datatypes.html#timing ), the eHealth Infrastructure does not enforce how elements of Timing can be used and combined. However, there is a recommended subset that the infrastructure understands and can help Patients and Clinicians to follow with reminders, alarms and an overview of expected and received measurements.
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