The Operation heading tells what kind of operation was performed and the associated time. All of these operations can be found both in the Activity History and in the Audit-Activity Log.
Four common Operations are defined below:
Secure Message: a Thru Email has been sent.
External Download: the attachments from the Thru Email have been downloaded. The downloaded attachments will be listed in the detailed layouts.
Internal Upload: a file has been uploaded by a user to attach to a Thru Email.
Thru Email Attachments Expired: a file has reached the Expiration date without being downloaded.