I think what they are alluding to is the fact that a certain number of hours spent as a Flight Engineer can count towards the 4,000 hours required by the airline.
Lasors 2010 states at G1.2:
Holders of a Flight Engineer Licence will be credited
with 50% of the flight engineer time up to a maximum
credit of
250 hours. This 250 hours may be credited
against the 1500 hours experience requirement
and the 500 hours requirement of a of G1.2 above
provided that the total credit given against any of the
above does not exceed 250 hours.
It seems that this airline (Emirates) is allowing an additional amount of time over and above that credited towards an ATPL as being allowed towards their requirement of 4,000 hours (500 hrs FE, rather than 250 hrs for the ATPL).
FOK 