This is a small but handy extension of the standard .NET DropDownList control in order to support an EmptyDataTemplate. The EmptyDataTemplate concept is used in other places to display some content when the bound datasource returns no results. It’s unfortunately not natively provided in the DropDownList, but I’ve found it to be very helpful.
I confess that this (at present) does not function fully like the normal EmptyDataTemplate usage, which is written as a child control. Rather, it’s simply an additional parameter. As such, it will really only support text.