This is where the system tracks user log-in and log-out data for the past 90 days only. This cannot be changed or deleted; however, users have the ability to change the visibility, width, and order of the columns.
Source shows whether or not the user manually logged out of UCM or forced off UCM by the Timeout settings (see “Company Timeout Administration” under Settings).
Time In/Time Out/Elapsed Time show timestamps when the user logged in/out and for how long (hours:minutes:seconds). Notice how blank Time Out fields also have blank Source fields?