This field contains the expected cost of the items, which is calculated by multiplying the Cost per Unit by the Valued Quantity.
When you post as invoiced, the program calculates the actual cost by using the Invoiced Quantity and Cost per Unit fields and uses this amount to fill the Cost Amount (Actual) field. In the same invoiced value entry, the program fills the Cost Amount (Expected) field with the balancing expected amount that will be posted to the G/L.