5. SUMMARY TAB
In the Summary tab (below), a table can be created that summarizes the chosen fields using different functions (Ex: Average, Count, Maximum, and so on). You can also make a group of fields by choosing the Group option from the Function dropdown menu.
Most actions and properties available in the Summary Tab are available in the Fields Tab.
The only difference is the removal of the Quick Add and Pivot capabilities, and addition of the Add Deltas checkbox
For more information on performing a Summary, refer to the Fields section.
Delta means "Change In".
Any time there is a change in a quantity that change is calculated by taking the later value for that quantity and subtracting from it the earlier value for that quantity.
This can be used in a report by selecting "Add Deltas" under the Summary tab. Select the "Add Deltas" checkbox under Summary tab
Result: The Deltas() show the change in the Unit Price over the period of time.