The GetDesignTimeValue method is a helper method used to determine what value to display for a field when rendering the BoundField object in a designer. If real data cannot be retrieved from the data source at design time, the value returned by this method is displayed instead.
This method is used primarily by control developers.
Notes to Inheritors:
When extending the BoundField class, you can override this method to return a different value to display for the field in a designer.