How Revenue Recognition value calculate in VF45 for an item

Hello Experts,

I want to know how system calculates Revenue Recognition for any item in VF45. I know the configuration part of Revenue Recognition but want to know the calculation part, how calculation going to find out the vale of the Revenue recognition.

Item net price is 3139255.45 and system calculate Revenue recognition for this item is 3139020.94.

I want to know how calculation going for Revenue recognition.

Can any body help me out ? any link /document related to Revenue Recognition Calculation (not configuration) please share with me.

Thanks,