Field help (BPSLOTSRH) 

If the product is managed by lot and this is a new lot manually entered, it is possible upon return to assign the original supplier lot if it is known (no specific control is carried out on this information).
When this is not the case, this information is not be accessible and it is initialized by the supplier lot associated with the internal lot if it exists (only a supplier lot can correspond to an internal lot).

A selection window is used to choose a supplier lot among known ones (that have the object of a receipt).
If several supplier lots are entered, data must not be entered in the return line but in the 'stock' detail window.