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For records indicating an audio / video call that has started- the relevant values are set and are used when filtering eDiscovery media records.
Messages Thread:
For each message there is Parent message ID.
When it is empty (NULL) - it is a root message and actually starts a new thread, and the thread ID is this message ID.
When it has value - it is a reply message to the thread started with the parent (root) message.
Meeting and group chat
Participants list includes link to Auditing. For a managed user the link is to the auditing records with the “From” value that match and for non managed users the link is to auditing records with the “To” value that match.
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