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  No place is possible: how do you know which place will cause the fewest changes?

In the display Timetable > Lesson > Timetable, select the lesson from the list on the left, then the option Diagnosis in the menu bar on the right.

• the number of lesson resources already occupied by a lesson that has no place elsewhere,
• the number of lesson resources already occupied by a lesson that has a place elsewhere (if moved, the selected lesson can be positioned in the slot),
• the number of resources with unavailability.

To see the concerned resources, click and drag the green frame over the slot to be diagnosed: they are displayed in red on the lesson form.