The five salary type columns can be used so that different employees can use the same absence codes during absence recording, but are giving different salary types. One common way of separating salary types is between salaried personnel (office or "white-collar" staff) and collective agreement employees (unionized factory workers or "blue-collar" employees). If you leave the salary type field empty, the corresponding absence code will not be shown for the employee in the Recording Terminal.
The headings for these columns are configured in the Settings procedure, and employees are linked to the right salary type column in either Group Settings or Update Employee.
Image of the "Salary type column for absence" setting in the Update Employee window.