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