Periods can easily be moved from one slot in the timetable to another using drag and drop.
Empty green cells denote slots in the timetable where a lesson may be scheduled without risk of clash. The different shades of green indicate the suitability of the positions for the dragged lesson. The darker, the better. The evaluation depends on the parameters you have entered (time requests, double periods, weighting, etc.).
Red fields indicate that the scheduling would be possible without clashes but the timetable would be significantly worse because of e.g. a blocking (time request -3). White fields show that scheduling without any conflicts is possible. The details window shows for which element a clash would occur.
Cells highlighted purple indicate that the room allocated to the lesson is not available.
When you move double periods or blocks, they are offered as double periods or blocks. However, if you only want to move one period, press the Ctrl. key and click into the timetable, similar to when you schedule periods. Double periods and blocks are now displayed as single periods and can be moved individually. If you want to have this function available permanently then go to the settings of the timetable, go to ‘Layout 2’, and check the box ‘Double periods like single periods’.