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()));