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;