function clip (id)
{
	if (document.getElementById("span_" + id).style.display == 'none')
	{
		document.getElementById("img_" + id).src = "img/minus.gif";
		document.getElementById("span_" + id).style.display = "block";
	}
	else
	{
		document.getElementById("img_" + id).src = "img/plus.gif";
		document.getElementById("span_" + id).style.display = "none"; 
	}
}