Informational 1xx *

This class of status code indicates a provisional response, consisting only of the Status-Line and optional headers, and is terminated by an empty line. HTTP/1.0 does not define any 1xx status codes and they are not a valid response to a HTTP/1.0 request. However, they may be useful for experimental applications which are outside the scope of this specification.

* Extracted from RFC 1945, "Hypertext Transfer Protocol -- HTTP/1.0", Berners-Lee, et.al., 1996