HttpResponseStrings

function HttpResponseStrings(code: integer): RawByteString;
begin
  case code of
    100: Result := '100 Continue';
    101: Result := '101 Switching Protocols';
    102: Result := 'Processing'; // WebDAV

    200: Result := 'HTTP/1.1 200 OK';
    201: Result := 'HTTP/1.1 201 Created';
    202: Result := 'HTTP/1.1 202 Accepted';
    203: Result := 'HTTP/1.1 203 Non-Authoritative Information';
    204: Result := 'HTTP/1.1 204 No Content';
    205: Result := 'HTTP/1.1 205 Reset Content';
    206: Result := 'HTTP/1.1 206 Partial Content';
    207: Result := 'HTTP/1.1 207 Multi-Status'; // WebDAV

    300: Result := 'HTTP/1.1 300 Multiple Choices';
    301: Result := 'HTTP/1.1 301 Moved Permanently';
    302: Result := 'HTTP/1.1 302 Found';
    303: Result := 'HTTP/1.1 303 See Other';
    304: Result := 'HTTP/1.1 304 Not Modified';
    305: Result := 'HTTP/1.1 305 Use Proxy';
    306: Result := 'HTTP/1.1 306 unused';
    307: Result := 'HTTP/1.1 307 Temporary Redirect';

    400: Result := 'HTTP/1.1 400 Bad Request';
    401: Result := 'HTTP/1.1 401 Authorization Required';
    402: Result := 'HTTP/1.1 402 Payment Required';
    403: Result := 'HTTP/1.1 403 Forbidden';
    404: Result := 'HTTP/1.1 404 Not Found';
    405: Result := 'HTTP/1.1 405 Method Not Allowed';
    406: Result := 'HTTP/1.1 406 Not Acceptable';
    407: Result := 'HTTP/1.1 407 Proxy Authentication Required';
    408: Result := 'HTTP/1.1 408 Request Time-out';
    409: Result := 'HTTP/1.1 409 Conflict';
    410: Result := 'HTTP/1.1 410 Gone';
    411: Result := 'HTTP/1.1 411 Length Required';
    412: Result := 'HTTP/1.1 412 Precondition Failed';
    413: Result := 'HTTP/1.1 413 Request Entity Too Large';
    414: Result := 'HTTP/1.1 414 Request-URI Too Large';
    415: Result := 'HTTP/1.1 415 Unsupported Media Type';
    416: Result := 'HTTP/1.1 416 Requested Range Not Satisfiable';
    417: Result := 'HTTP/1.1 417 Expectation Failed';
    418: Result := 'HTTP/1.1 418 I''m a teapot';
    422: Result := 'HTTP/1.1 422 Unprocessable Entity'; // WebDAV
    423: Result := 'HTTP/1.1 417 Locked'; // WebDAV
    424: Result := 'HTTP/1.1 424 Failed Dependency'; // WebDAV
    425: Result := 'HTTP/1.1 425 Unordered Collection'; // WebDAV
    426: Result := 'HTTP/1.1 426 Upgrade Required';
    449: Result := 'HTTP/1.1 449 Retry With';
    450: Result := 'HTTP/1.1 450 Blocked by Windows Parental Controls';

    500: Result := 'HTTP/1.1 500 Internal Server Error';
    501: Result := 'HTTP/1.1 501 Method Not Implemented';
    502: Result := 'HTTP/1.1 502 Bad Gateway';
    503: Result := 'HTTP/1.1 503 Service Temporarily Unavailable';
    504: Result := 'HTTP/1.1 504 Gateway Time-out';
    505: Result := 'HTTP/1.1 505 HTTP Version Not Supported';
    506: Result := 'HTTP/1.1 506 Variant Also Negotiates';
    507: Result := 'HTTP/1.1 507 Insufficient Storage'; // WebDAV
    509: Result := 'HTTP/1.1 509 Bandwidth Limit Exceeded';
    510: Result := 'HTTP/1.1 510 Not Extended';
  else
    Result := 'HTTP/1.1 ' + RawByteString(inttostr(code));
  end;
end;

http://code.google.com/p/delphionrails/source/browse/trunk/src/dorHTTP.pas