No, that's the catch. They only give whole 28-day periods off. They call that part-time.
For the rest one can use the 42 days vacation. Must take minimum of 5 days vacation at a time. So in 8 periods you will have 16 of 28 days off.
In every 28-day period one has 9 days off. They come as a block of 3 and 6. Before these one has 24hrs rest. So that will be every 28-day period 11 days off (including rest). With 5 days vacation on top of that gives 16 days. This can be done 8 out of 13 rosters (40 days). 2 days to spare.
42 days vacation with no part-time!