SKOLM02A is an inventory of students activitiesat the Danish music schools. A student may have several courses associated with different programs at a music school. The category 'unknown' is an invenory of students courses that have either had invalid personal data or have been removed because of discretion. The students who have a course, but unknown gender and age have invalid personal data. The students who have unknown courses are mainly removed because of discretion. The table SKOLM02B is an inventory of the unique number of students at the Danish music schools.Due to a lack of reporting "companion students" in the schools' student administration system for a municipality in the 2021/22 season, the number of activity students for "preschool" and thus "students in total" is approximately 500 activities students too low.