This is the "adjusted FBA fees". Column S 'fba fees' contains shipping and gift wrap totals. These are subtracted from the adjusted fba fee. Multi-channel fulfillment orders are also excluded since the fees are not consistent with regular fba fees. These orders have an Order-ID beginning with 'S'. We account for orders that received a promotional discount as well. In other words if you gave out a coupon code, that amount is subtracted from the fee total.
Also, we've tried to take into account orders with multiple quantities. The adjusted fee divides by the quantity as to make the fee per item rather by order. Any change in fees will have to be greater than the calculated threshold to trigger an issue regardless of how many items are in an order.