A work shift shall be mixed where it includes day and night work. A mixed work shift with 4 or more hours of night work shall be deemed a night shift and shall have the duration of a night shift, and if it covers less than 4 hours of night work, it shall be deemed a day shift and shall have the duration of a day shift (). The rotation of shifts in the enterprise shall be specified by the Internal Rules of Procedure (). The work shifts of the employees who are continuing their education while under employment, as well as of high-school students working in their free time, shall be specified depending on the organisation of their studies (). It is prohibited to assign work for two consecutive work shifts (). For enterprises with a continuous work process the employee shall not leave work before the arrival of the respective employee from the next shift without the permission of his/her immediate superior. In such cases the immediate superior shall take the necessary measures to find a substitute ().
The employer can establish aggregate calculation of the working hours - weekly, monthly or over a different calendar period, which cannot exceed 6 months (). Aggregate calculation of the working hours shall not be allowed for employees on open-ended working time (). The maximum duration of a work shift under aggregate calculation of the working hours can be up to 12 hours, whereas the duration of the working week may not exceed 56 hours, and for employees at reduced working hours it can be up to one hour beyond their reduced working hours ().