Ajuda p/o campo (KFSMI) 

This field concerns the basis subject to tax of an invoicing element for which the including tax calculation basis is equal to the including tax amount.
The basis of an invoicing element with an excluding tax calculation basis is equal to the excluding tax amount of the invoicing element.
When the invoicing element has a product rate tax rule, you can display the distribution of the basis subject to product tax using the Actions icon.