B. modify the original Vat calculation method, which is calculated from the total amount of the entire document, changes to Vat is calculated for each Item and then apply the amount of any Item.
b. revised method of calculating Vat, which is calculated from the sum of the whole document. Vat change to the calculation of each Item, took the top of every Item comes together.
B correction method Vat which was estimated from the total amount of the whole document, change is calculated Vat of each Item and took the top of all Item together