LosP. - is correct.
However not all station staff are aware of this. The port I regularly fly out of and who’s staff I’m friendly with told me they were surprised during their recurrent training test in Dubai on how many outstation colleagues are not aware of this and thought it was pure seniority. One would have thought that the system catches it - not always.
That’s why FABS can help you in a tight spot - if there are 10 on stby and one seat going & you are most junior but it shows you as the only one booked First - that’s your seat - regardless of class of seat available.
Had a situation where this occurred at my home port but the seat was not awarded to me - quickly went to ask and sought clarification- new staff member requested help and I got the last and only ECON seat.
If the station Senior is not aware - politely ask them to call Dubai & clarify if you are not put on.
This happened in summer 2016 - im not aware of any policy change since.
That why it’s always better to book highest class on tight loads.