When doing your Setup of your Calendar, here is the different categories of day / Day types:
Normal: students are expected to attend school today.
Holiday: a statutory holiday.
Special: professional activity/development day where students do not attend school.
Board Holiday: a non-school day affecting all schools in the board such as March/Spring Break.
Grant: an unexpected closure such as weather or no heat in the school.
Exam: (secondary schools only) exam day for the whole school. Regular period class attendance is disabled for these dates, however exam day attendance is available to record am/pm attendance.