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;