img = new Array(13);
	if (document.images) {
	img[0]=new Image();       
	img[0].src = "";
	img[1]=new Image();       
	img[1].src = "../images/homepage/who_rol.gif";
	img[2]=new Image();       
	img[2].src = "../images/homepage/services_rol.gif";
	img[3]=new Image();       
	img[3].src = "../images/homepage/operations_rol.gif";
	img[4]=new Image();       
	img[4].src = "../images/homepage/clients_rol.gif";
  img[5]=new Image();       
	img[5].src = "../images/homepage/contact_rol.gif";
	img[6]=new Image();       
	img[6].src = "../images/subpage/services_oil_gas_roll.gif";
	img[7]=new Image();       
	img[7].src = "../images/subpage/services_transportation_roll.gif";
	img[8]=new Image();       
	img[8].src = "../images/subpage/services_environmental_roll.gif";
	img[9]=new Image();       
	img[9].src = "../images/subpage/services_residential_roll.gif";
	img[10]=new Image();       
	img[10].src = "../images/subpage/services_biophysical_roll.gif";
  img[11]=new Image();       
	img[11].src = "../images/subpage/services_international_roll.gif";
	img[12]=new Image();       
	img[12].src = "../images/subpage/services_first_roll.gif";
	
		}
		
		currentIndex = 0;
		oldsrc = "";
		function on(index) {
		    if (document.images) {
		      currentIndex=index;
		      oldsrc = document.images["main"+index].src;
		      document.images["main"+index].src = img[index].src;      
		    }
		}
		function off() {
		    if (document.images)
		      document.images["main"+currentIndex].src = oldsrc;
    }