function fnNavAppear(intNavItem)
{
   document.getElementById('page_mainnav_link_'+intNavItem).src=document.getElementById('page_mainnav_link_'+intNavItem).src.replace("off","on");
}

function fnNavClear(ex)
{
  for(var i=0; i<6; i++)
  {
     if(i!=ex)
      document.getElementById('page_mainnav_link_'+i).src=document.getElementById('page_mainnav_link_'+i).src.replace("on","off");
  }
}