Output Level LEDs

[HBIII]

Are these measuring dBu or VU? So for example if the led lights up at 0 am I getting 0dBu or +4dBu?

And I guess the levels on the actual LCD screen are in dBFS? So the line down the center is -12dBFS=6dBu (assuming 0dBu = -18 dBFS)?

Just trying to get my gain staging correct and the manual is not very clear (The level diagram in the back is very confusing :-/).

Thanks!