Subtotal 3 field in SALES

Dear Users,

I have a question to understand what is teh difference between the NET VALUE and Subtotal 3 from Sales order level.

I have attached a doc where you can see the values for these fields in BW and in ECC. The NET value field is marked.

Most of the time i see the NET value and subtotal 3 being same. But for some cases like attached one there is difference.

I do not know which condition type is this subtotal 3 field considering from the ones mentioned in the screen print in doc. Is there any place i can what condition types or calculations is it using to come to the value shown in BW. Or is straight picking up value from any of the condition types?

Please advise.

Regards

Zabi