[____ANGEL___]

I have already observed it several times!
WINKFP uses a different ZB as the last update, ISTA-P also takes other parameters into account!
But I would also be interested in the exact method! 

Because as i several times wrote here in this forum, winkfp does not take care of VO and I-STEP SHIPMENT.... Calculation of sw numbers is based on VO and I-STEP SHIPMENT as for F series and also G and I. So determining a zb with HIS file will be wrong and also choosing update zb in winkfp will be wrong. I suggest you to spend your time learning about NFS and you will understand all about this argument and you will learn how to calculate numbers manually (that is what NFS does automatically infact nfs for making a flash wants to know i-step shipment and vo and can flash a car using 3 icom channels simultaneously wich is a must in that era)

Thank you for your explanation. When i calculated the zb number in the previous post, was it correct? Or did i miss something. I know that NFS does that automatically, but just to clarify if my understanding is correct.

That is a particular case where interchangeable zb are available, 9383040 and 9390481, basically with NFS method we have to use to use 9383040... Check in nfs guide how to sort interchangeable zb. Anyway your kmm interpretation is correct.