Mic Position Using REW

I'm somewhat confused by the mic positioning when using REW to measure room acoustics at a mixing desk.



I believe the instructions state to place the mic at the listening position with the diaphram pointed toward the ceiling. This in counter intuitive to me.



Should the mic be positioned at the mix station pointing toward the monitors, or the ceiling? If the ceiling, why is that? We don't record anything that way.



Thanks....!

Mic Position Using REW