Para consultar los codigos devueltos por servidores HTTP puedes consultar esta pagina:
http://www.faqs.org/rfcs/rfc2616.html302 = Found.
The requested resource resides temporarily under a different URI.
Since the redirection might be altered on occasion, the client SHOULD
continue to use the Request-URI for future requests. This response
is only cacheable if indicated by a Cache-Control or Expires header
field.
The temporary URI SHOULD be given by the Location field in the
response. Unless the request method was HEAD, the entity of the
response SHOULD contain a short hypertext note with a hyperlink to
the new URI(s).
If the 302 status code is received in response to a request other
than GET or HEAD, the user agent MUST NOT automatically redirect the
request unless it can be confirmed by the user, since this might
change the conditions under which the request was issued.
Note: RFC 1945 and RFC 2068 specify that the client is not allowed
to change the method on the redirected request. However, most
existing user agent implementations treat 302 as if it were a 303
response, performing a GET on the Location field-value regardless
of the original request method. The status codes 303 and 307 have
been added for servers that wish to make unambiguously clear which
kind of reaction is expected of the client.
El codigo 315 no esta documentado

De todos modos los codigos 3XX se refieren a redirecciones generalmente:
10.3 Redirection 3xx
This class of status code indicates that further action needs to be
taken by the user agent in order to fulfill the request. The action
required MAY be carried out by the user agent without interaction
with the user if and only if the method used in the second request is
GET or HEAD. A client SHOULD detect infinite redirection loops, since
such loops generate network traffic for each redirection.
Note: previous versions of this specification recommended a
maximum of five redirections. Content developers should be aware
that there might be clients that implement such a fixed
limitation.
Mclaud, el codigo que das no sera del sistema operativo? son dos cosas distintas.