Clears any headers that might have been set previously.
This clears all the header definitions that might have been added with HttpResponse.AppendHeader.This throws an System.Web.HttpException if the headers have already been sent to the client (for example, if the user has called the HttpResponse.Flush method.
Namespace: System.Web
Assembly: System.Web (in System.Web.dll)
Assembly Versions: 1.0.5000.0, 2.0.0.0