Suppose you want to calculate the GST and DISCOUNT for a Net Value of 1000.
Net value                                    1000
GST 10%              of 1000           100
DISCOUNT 10% of 1000           100

Final Net value         900

This is what you do :-

• M/08 - Define calculation schema
• First check the conditions column Steps e.g. PB00 and PBXX belongs to step 1.
• Next check the last Steps after Actual Price
• Now, look at the column Fro To
• If you want the DISCOUNT to be calculated based on 1000, put the Steps number in the column Fro

The Fro To controls the calculation.