If several time restrictions have an effect on a lesson, the following rules apply:
Overlapping of terms with lesson groups and "from/to" restrictions
Lesson groups and "from/to restrictions" are effective regardless whether terms are available or not.
Lesson data can be saved term-wise as described in the chapter "How to change data within a term". If a lesson has a time restriction due to being non-existent, the lesson does never take place.
Overlapping of lesson groups and "from/to" restrictions
The lowest common denominator applies to overlaps of lesson groups and "from/to" restrictions. If there are no overlappings, the lesson never takes place.
If there are contradictory entries of lesson groups and "from/to" restrictions, the "from/to" restriction of the lesson applies.