This field is used to mark items as deposit items.
This is used when printing the number of sold items on the receipt. A common use for linked items is to link bottles to soft drinks so that bottles can be collected independently
of the price of the soft drink. In these cases we do not want the soft drink and the bottle to be counted
as separate items but as one. If the deposit item flag is set the system will not include the linked
item in the number of items sold which is printed on the receipt.