In this field you can specify a particular item ledger entry to which you wish to apply the current service line. This field is used in case the type on the service line is Item.
If you enter an item ledger entry number in this field, this will mean that the inventory decrease from this service line will be taken from the inventory increase in the item ledger entry selected. This creates a link so that the cost of the applied-to item ledger entry is carried over to this line. To see a list of the entries that you can apply to, click the AssistButton to the right of the field.