Field help (SFIDSPLIN) 

These parameters are used to specify whether the calculated amounts at the footer can be distributed on the different document lines in proportion to the amounts, quantities, weights or volumes.
The distributed elements do not impact the line net price for the document line. On the other hand, these distributed invoicing elements will impact the product statistics, the accounts, the analytical dimensions for the invoice lines (and thus the revenue) generated in accounting as a function of the automatic journal associated with the invoice type.
SEEINFO For a single invoice, a maximum of nine invoicing elements distributed on the lines can be used.