有这样一段代码，不知道啥意思
routes.MapRoute(
"ChangeLanguage",
"ChangeLanguage/{id}",
new { controller = "Home", action = "ChangeLanguage" },
null,
new string[] { Namespace }
);

RouteValueDictionary defaults = new RouteValueDictionary();
RouteValueDictionary constraints = new RouteValueDictionary();
RouteValueDictionary tokens = new RouteValueDictionary();

defaults.Add("controller", "home");
defaults.Add("action", "index");
defaults.Add("data", string.Empty);
constraints.Add("data", @"[a-zA-Z0-9\-]*");
tokens.Add("namespaces", new[] { Namespace });
tokens.Add("pageId", 0);

routes.Add(new Route("", defaults, constraints, tokens, new MyRouteHandler()));