function LinksExternos(){
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") == "externo")
		anchor.target = "_blank";}}
window.onload = LinksExternos;