function externalLinks() {

if (!document.getElementsByTagName) return;

var anchors = document.getElementsByTagName("a");
for (var i=0; i<anchors.length; i++) {
var anchor = anchors[i];
var relvalue = anchor.getAttribute("rel");

if (anchor.getAttribute("href")) {
var external = /external/;
var relvalue = anchor.getAttribute("rel");
if (external.test(relvalue)) { anchor.target = "_blank"; }
}
}
}
/*
// NB: ook in de body vermelden: onload="externalLinks();"
// deze functie doet hetzelfde:
window.onload = externalLinks; 
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;
*/