var agt = navigator.userAgent.toLowerCase();
	var is_major = parseInt(navigator.appVersion);
	var is_nav = ((agt.indexOf('mozilla') != -1) && (agt.indexOf('spoofer') == -1) && (agt.indexOf('compatible') == -1) && (agt.indexOf('opera') == -1) && (agt.indexOf('webtv') == -1));
	var is_nav4up = (is_nav && (is_major >= 4));
	var is_ie = (agt.indexOf("msie") != -1);
	var is_ie3  = (is_ie && (is_major < 4));
	var is_ie4  = (is_ie && (is_major == 4) && (agt.indexOf("msie 5") == -1) && (agt.indexOf("msie 6") == -1));
	var is_ie4up = (is_ie && (is_major >= 4));
	var is_ie5up  = (is_ie  && !is_ie3 && !is_ie4);
	var is_mac = (agt.indexOf("mac") != -1);
	var is_gecko = (agt.indexOf("gecko") != -1);

	function grabObject (id) 
	{
		if (is_ie4)
		{
			var view = eval(id);
		}
		
		if (is_ie5up || is_gecko)
		{
			var view = document.getElementById(id);
		}
		
		return view;
	}

	function show_hide(id)
	{
		var hdn_div = grabObject('hdn' + id);
		var shdn_span = grabObject('shdn' + id);
		var xpand_img = grabObject('image' + id);
		
		if(hdn_div.style.display == 'block') 
		{
			hdn_div.style.display = 'none';
			xpand_img.src = 'imagenes/plus.gif';
		} 
		else 
		{
			hdn_div.style.display = 'block';
			xpand_img.src = 'imagenes/minus.gif';
		}
	}