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 = Custom.init;
if (window.addEventListener) { // If they're using a W3C Event Model compliant browser
  window.addEventListener("load",externalLinks,false);
}
else if (window.attachEvent) { // If they're using IE
  window.attachEvent("onload",externalLinks);
}