function openCenteredWindow(url, width, height, name, parms) {
  var left = Math.floor( (screen.width - width) / 2);
  var top = Math.floor( (screen.height - height) / 2); ",width=" + width + ",resizable=1,menubar=0,toolbar=0,location=0";
  if (parms) { winParms += "," + parms; }
  var win = window.open(url, name, winParms);
  if (parseInt(navigator.appVersion) >= 4) { win.window.focus(); }
  return win;
}

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";
 }
}