Time ranges which were defined as holidays in the timetable mode, are automatically displayed as "No lessons".
In addition to the settings in the holiday calendar ("Settings | Holidays"), you can define in the form view of the calendar if certain days do not have lessons or if they are (public) holidays, by selecting the day and the required option. This differentiation is important in some countries with regards to teacher salaries.
Regionally different analyses procedures are defined in the "Settings | School data" (country, region, type of school). Depending on which country and which type of school is defined, it can happen that the analyses of the same substitution data are different.
In the "Only these periods free of lessons" field, you can enter periods in which the entire school has no lessons.
If due to great heat, all periods after period 5 are cancelled, enter "6-8"; if there is no lesson in period 1 due to a mass, and period 5 has no lessons due to a school event, enter "1,5".
The periods without lessons are displayed in the timetable as "free". If a reason of absence has been entered, then it will be displayed in the timetable.