Okay, that is clear now, thanks!
Anyway, I forgot to mention that training is not included in those work days: when we have a training session, it is usually from 0830 till 1400, and they put it in your roster the day before a cycle begins: 2 earlies, 2 lates, 1 night/day, 2 off (or sleep day plus 1), training ... So, de facto, this cycle is a 5 on 2 on 1, and the next is a 6 on 3.
Other 6 on 2 are scheduled in heavy traffic seasons like Summer or Passion Week, or any time the managers decide it is necessary. All these extra working days add nothing to your salary, and were not included in my former calculations.