we purchase a option, premium is 10000 USD, during tbb1 posting, we post to B/S account for premium, at the end, we transfer to P/L using "post and fix derived business transaction", thus I am confused, because premium flow type is not derived business transaction, why should we use this transaction, what's the purpose of this transaction?
why we can't post to premium expense P/L at TBB1 in the begining?