The site uses “winter school holidays” as a practical umbrella for the nationwide Christmas holidays and the one-day half-year holiday. These periods are simpler than spring holidays because the dates do not vary by kraj.
Christmas holidays
The official school-year calendar defines the start and end of the Christmas break. The engine stores those dates explicitly for each supported school year.
Half-year holiday
The one-day half-year holiday is also national. It can create a convenient family long weekend when it falls next to Saturday and Sunday.