function popup() {
  var i,p,d,obj,args=popup.arguments;
  for (i=0; i<(args.length-2); i+=3) 
  with (document) if (getElementById && ((obj=getElementById(args[i]))!=null)) { d=args[i+2];
    if (obj.style) { obj=obj.style; d=(d=='mostrar')?'block':(d=='ocultar')?'none':d; }
    obj.display=d; }
}