function ext() { 
	if(!document.getElementsByTagName) { return; }
	var as = document.getElementsByTagName("a"); 
	for(var i = 0; i < as.length; i++) { 
		if(as[i].getAttribute("href") && as[i].getAttribute("rel") == "ext") { 
			as[i].target = "_blank";
		}
	} 
} 
window.onload = ext;