function extLinks() {
if (!document.getElementsByTagName) return;
   var anchors = document.getElementsByTagName("a");
   for (var i = anchors.length; i != 0; i--) {
       var a = anchors[i-1];
       if (!a.href) continue;
       if (a.getAttribute("rel") == "external") {
           a.target = "_blank"; }
   }
}