Period of validity and caching of a Participant Metadata Set

Period of validity

Participant Metadata Set is valid 7 days from the time it was fetched. The exact date and time is found in the field notvalidafter.


Each participant is required to retrieve a new list with a frequency of at least two times the interval value. Currently interval is set to 24 hours. In other words: Every second day.


Each participant is responsible for

  • retrieving the list and store it in their central/master system
  • distributing the list to their own units, think validators

Caching and ETag

Since 2021-12-07, participants are recommended to cache the Participant Metadata Set for up to 1 hour before making an attempt to update it. This value is specified by the Cache-Control max-age response header. After that it is recommended to use ETag and the If-None-Match request header to conditionally get a new Participant Metadata Set only if it is updated. If update is not possible for some reason, the previously fetched Participant Metadata Set is valid for 7 days.


More information in MTS4, found at