...
The Discount,% and Discount (or Discount Price) columns are available if the Enable discounts and markups in sales documents option is selected on the Administration > Settings > Sales form. Use these columns to specify the manual discount granted to the customer. The default discount can be set in the customer contract. The Auto-Discount % and Auto-Discount columns are available if the Enable Automatic Discounts and Markups option is selected on the Administration > Settings > Sales form. Non-zero values in these columns indicate that one or more discounts are applied because their conditions are met in the document.
The values in the Amount column are automatically calculated for each item according to the specified priceprices, quantityquantities, and discountdiscounts.
If the VAT Applied option is selected for this document on the Main tab, the VAT, % and VAT Amount columns are available. The VAT amount is calculated in the currency of the document according to the amount and VAT-related settings (which are specified on the Main tab) as follows:
...