The AllowSortBySummary property is applied if the current field is a Column Field or Row Field. If the AllowSortBySummary property is set to true and the current field is a column field, end-users can sort the current field's values by summary values in other rows. If the current field is a row field, end-users can sort the current field's values by summary values in other columns. For end-users, this type of sorting is available via context menus, invoked when right-clicking an innermost column or row header.
