function apri(cat,num) {
	
	for (i= 1; i < num; i++) 
	{
	//	alert(document.getElementById('tr_'+i).style.visibility);
		if (document.getElementById('tr_'+cat +'_'+i).style.visibility == "visible")
		{
		document.getElementById('tr_'+cat +'_'+i).style.visibility = "hidden";
		document.getElementById('tr_'+cat +'_'+i).style.position = "absolute";
		document.getElementById('fr_'+cat).src = "/img_ec/freccia_btn_ec.gif";	
		}
		else
		{
		document.getElementById('tr_'+cat +'_'+i).style.visibility = "visible";
		document.getElementById('tr_'+cat +'_'+i).style.position = "relative";
		document.getElementById('fr_'+cat).src = "/img_ec/freccia_down_btn_ec.gif";
		}
	}
	
}
function azzera()
{
//	alert("class " +document.getElementById("td_home").className);	
	document.getElementById("td_1").className = document.getElementById("td_1").className;
}