function showHideSubMenu(menu)
	{
		displayItem = document.getElementById(menu).style;
		if (displayItem.display == 'none')
			// it displays the content of the selected item and close all the others
			{
				displayItem.display = '';
				document["arrow"+menu].src = "/images/arrow_on.gif";
				
				// loop around the array to 'close' the content and change the arrow
				for(num=0; num < array_section.length; num++)
				{
					var_item = array_section[num];
					if (var_item != menu)
					{
						if (document.getElementById(var_item).style.display != 'none')
						{					
							document.getElementById(var_item).style.display = 'none';
							document["arrow"+var_item].src = "/images/arrow_off.gif";
						}
					}
				}
			}
		else
		{
			displayItem.display = 'none';
			document["arrow"+menu].src = "/images/arrow_off.gif";
		}
	}