Gathers information about the server control and delivers it to the Page.Trace property to be displayed when tracing is enabled for the page.
This property gathers the information necessary about a page's UI hierarchy and passes it to the page's <trace> Element property. When you enable tracing, either for a page or for your application, this information is displayed in the Control Tree section of the trace output. Trace output for a page is appended to the end of the page; while trace output for an application can be viewed from the trace viewer (trace.axd file) which is stored in the application's root directory. For more information about tracing, see ASP.NET Tracing Overview.