Reservation Qty check

Hi Experts,

I would like to now How is open reservation qty is calculated as per below scenario

Material 4100000024 has 146 pcs Unrestricted stock, 129 pcs reserved stock, 197 on order stock, and 90 in GR blocked stock

please check how this 54 pcs is calculated. My checking rule is 03 n availability check is 02.

Thanks