function preLoad() {
   var d=document; 
   if(d.images){ 
      if(!d.onArray) d.onArray=new Array();
      if(!d.offArray) d.offArray=new Array();
      if(!d.nameArray) d.nameArray=new Array();
      var j=d.onArray.length,arg=preLoad.arguments; 

      for(var k=0; k < arg.length; k++)
         if (arg[k].indexOf("#") != 0) { 
            d.nameArray[j] = "menu" + arg[k];
            d.onArray[j] = new Image;
            d.offArray[j] = new Image;
	    d.onArray[j].src = "./img/on" + arg[k] + ".gif";
            d.offArray[j++].src = "./img/off" + arg[k] + ".gif";
         }
  }
}

function change(oper, ndx) {
   var d = document;

   if (d.images) {
      n = d.nameArray[ndx];

      if (oper == 'on')
         d.images[n].src = d.onArray[ndx].src;
      else
         d.images[n].src = d.offArray[ndx].src;
   }
}