+=head2 response_code()
+
+=head2 response_headers()
+
+=head2 response_page()
+
+These three fields are set by some processors (especially those which use
+HTTPS) when the transaction fails at the communication level rather than
+as a transaction.
+
+response_code is the HTTP response code and message, i.e.
+'500 Internal Server Error'.
+
+response_headers is a hash reference of the response headers
+
+response_page is the raw content.
+