This delves into the intracacies of aviation legislation and CX company policy, so perhaps only the professionals can give you a definite answer. That said, my general understanding is as follows:
1. Calculating and logging P2X time is used to summarize the time for which an S/O is at the controls of the aircraft. I think of it as a calculation of block hours for S/Os, which is obviously calculated in a different way from F/Os and CNs.
2. The annual flying hours limit is imposed on the credit hours and not block hours.
3. Block hours = Off-Chocks to On-Chocks
4. Credit hours = All time at work including block hours, i.e. from signing on at CX City to signing off at the outport.
Summing up the these points, my understanding is that while an S/O does not log all the time in the air, his total duty time is what counts towards the annual flying limit, as such it is why he cannot be rostered flights as frequently as an F/O or CN.
I hope this makes sense. If it is wrong in any way, please don't flame me and feel free to make corrections!
