WBF
That is what I also meant. This is from actual bulletin
GW and CG values are computed from entered ZFW and ZFWCG corrected for the predicted FOB and CG variation. When the Approach phase is activated, the characteristic speeds are recomputed using the actual weight and CG.
The performance model used to compute the characteristic speeds, is accurate enough to provide speed errors of less than ± 2 kt from the certified speeds.
Off course few knots practically makes no difference