Field help (PFIDACORD) 

Two values are proposed:

An invoicing element set up to be present at the order line is an element that the user can associated with a price list structure, that is to say that at the time of the column setup the columns allow the entry of price lists on the different order lines.
SEEREFERTTO See the documentation on the price list structure for further information.

Only the elements belonging to a structure code defined at the level of the supplier BP record can be taken into account at the time of order entry for the same supplier.
Specific case
It is not possible to set up a rate for an element used at line level. If needed, the rate must be set up at the level of the price list structure. The (invoicing element) total corresponds to an actual amount of the discount or of the charge in percentage, which is calculated in the order line.
An invoicing element set up to be present in the order footer is an element which can be found in the order footer. This element must be specified for each supplier (in the supplier BP record) in the gird 'Discounts and charges'.
Only the footers specified at BP record level can be taken into account by default in the Purchase order.

If an invoicing element is not defined as being on the order line or order footer, it can still be associated with a supplier.
It will be used automatically upon supplier invoice creation by using the default value defined in the supplier record.
An invoicing element defined on order footer or on invoice footer (not defined as being on order line or order footer) can be entered, when this is necessary, for a supplier invoice even if the element does not exist in the supplier record.