function linksExternos() {
                if (!document.getElementsByTagName) return;
                var anchors = document.getElementsByTagName("a");
                for (var i=0; i<anchors.length; i++) {
                        var anchor = anchors[i];
                        anchor.tabindex = i;
                        if (anchor.getAttribute("href") && 
anchor.getAttribute("rel") == "external")
                                anchor.target = "_blank";
                }
        }

        window.onload = linksExternos;