Th IResponse::put_Buffer method sets the value of the Buffer property of the Response object.
HRESULT put_Buffer(
VARIANT_BOOL fIsBuffering // contains the new Buffer value
);
When page output is buffered, the server does not send a response to the client until all of the server scripts on the current page have been processed, or until the Flush or End method has been called.
The Buffer property cannot be set after the server has sent output to the client. For this reason, the call to Response.Buffer should be the first line of the .asp file.
Response Object, IResponse::get_Buffer