The Trade Union setting here is nearly the same as above (pension funds), but there are some more % variables that must be filled in because of the special agreement with the trade union.
There is also an extra record No.1 which is for those who not belong to any trade unions.
If the trade union collects the fee, you also need to define the trade union under Pensions / Collectors.
Click 
to select and register dues that belong to trade union:
Some does are optional for an employee and therefore you must add it where you register salary items for employees.
If a due does not appear there it is calculated for all employee that belong to the trade union.
Holidays period shows the period of the year dedicated to holidays according to trade union contract.
Some contracts have another period and then this should be changed. The year here is always the current year and needs not to be changed.