function on(name,path) {                                     
   eval("document.images[\"" + name + "\"].src = \"" +               
      path + "/" + name + "_on.png\"");                                                                         
}                                                                     
                                                                      
function off(name,path) {                                           
   eval("document.images[\"" + name + "\"].src = \"" +               
      path + "/" + name + "_off.png\"");                                                                           
}