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;