You can lock periods in the timetable that have been scheduled long in advance. This is now possible for cover planning.
Clicking on the icon with a lock results in the lesson in question being locked. Under <Grid Adjustment> you can also display the column 'Lck (X)'. This column is for informational purposes only and cannot be used to make changes.

If you attempt to change this substitution at a later point in time, a message will be displayed indicating that it is locked.
