function select_main(id)
{
document.getElementById("main_"+main_sel).className="mod_prod_off";    
document.getElementById("main_"+id).className="mod_prod_on";    
document.getElementById("list_"+main_sel).style.display="none";    
document.getElementById("list_"+id).style.display="block";  

main_sel = id;
}

function select_only(id)
{
document.getElementById("main_"+main_sel).className="mod_prod_off";    
document.getElementById("main_"+id).className="mod_prod_on";    
document.getElementById("list_"+main_sel).style.display="none";    
//document.getElementById("list_"+id).style.display="block";  

main_sel = id;
}