function ShowNxt(idx)
{
   if (document.getElementById)
   {
      var displayMode = "";
      var names = new Array( "ts", "sem", "web", "spec");


      // If the parameter is 0, only the intro text is  displayed:
      for (i = 0; i < 5; i++)
      {
         displayMode = (i == idx) ? "block" : "none" ;
         document.getElementById(names[i]).style.display = displayMode;
      }
   }
}