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