In Norway, this event varies from school to school. It is usually held during the winter months, and is often called "Nyttårsball" which means "the new years ball." The students are not allowed to bring people from outside the school. In Norway, it is the norm to have proms for 8th, 9th, and 10th graders at Norwegian middle school, and most of the time, there is no division between formal and grad – students can attend in whatever clothing they choose, such as traditional knee-long dresses.