Don't make the FLI more complicated than what it is. It is tQ, T4 and N1 combined in 1 needle on a scale of power usage vs power remaining which is biased in other words take into account atmospheric conditions. The VEMD calculates which limit is your first limiter and that determines the needle position of the FLI. The digital raw signals for tQ, T4, n1 on the rH side will be underlined by yellow or red dependant on the limit reached and which one is affected. On the B3 and B4 the VEMD will also monitor and record the overlimit reached dependant on ground speed for TQ as it is dependant on whether you are above or below 40kts-the vEMD has a pitot static line for this and the biased calculations. How it is done in detail is the secret of THALES as it is there software as is the DECU's.