Group Summary Items Page
Grid Views and their descendants provide a summary feature that allows the values of aggregate functions that have been calculated against all the rows or only groups of rows to be displayed. To calculate and display summary values for groups of rows, you need to add the group summary items to the View's GridView.GroupSummary collection. Each summary item specifies the type of an aggregate function, the field whose values are used for calculations, whether summary values should be displayed in group footer cells or in group rows, etc. The designer's Group Summary Items page provides access to the collection of group summary items and allows the settings of individual items to be customized. This page is shown in the image below.
The Add button creates a new summary item and appends it to the collection. The Remove button removes the selected item from the collection. The available summary items are listed within the list box. The selected item's settings are displayed within the property grid.
For detailed information on group summaries, see the Group Summary document.