asp.net - Why are these HttpResponse methods not allowed in "asynchronous postback scenarios"? -

I was reading to get some more information about the HttpResponse class. Although I came up on a strange comment.

The following methods of the HttpResponse class are supported only in the postback scenario and are not in:

  Clear BinaryWrite ClearTontent Clearheaders Close End Flush TransmitType Write TypeFile WriteSubstubeStation    
 What does this really mean? I depend heavily on HttpResponse. Write me in a project. What is actually a  asynchronous postback scenario ?   
 
 
 An async postback occurs when you can post something like an updatePanel.  
 A large difference in Enscape postback is in the render.  
 Your normal prerender and render logic call will not be called.  
 Only a part of the page is updated at the front-end using Javascript.  
 This means that you can not return another document, change the http header, etc.