The Assignment History screen provides a list of all changes in the class assignments made manually using Suggestions screen since the timetable was created/loaded (and there is a line for each change made using the Suggestions page). Click on any of these changes to see a suggestion that will "undo" this change.
The only item in this section is
Simplified mode
When checked, only additional student conflicts are displayed for each change
A list of changes in time/room assignment that includes a time stamp for each of them. Click on any of these changes to see a suggestion that will "undo" this change.
Apply
Apply changes made to the filter
Export PDF
Export the list of changes to a PDF document
Refresh
Refresh the screen