A script that, when run on a client, will initiate a callback to the Web server.
Implementations of the ICallbackContainer.GetCallbackScript(IButtonControl, string) method should return a script that, when run on the client, will initiate a callback to the Web server.
The argument parameter is passed to the System.Web.UI.ICallbackEventHandler.RaiseCallbackEvent(string) method that handles the callback.
For more information on creating callbacks, see Implementing Client Callbacks Without Postbacks in ASP.NET Web Pages.