function imgOn(n) {
		var cmd = "document.menu" + n + ".src='images/menu" + n + "a.gif';";
		eval (cmd);
	}


	function imgOff(n) {
		var cmd = "document.menu" + n + ".src='images/menu" + n + ".gif';";
		eval (cmd);
	}


	function changeLayerVisibility(layer_id)
	{
		var state = "visible"

		if (document.getElementById(layer_id).style.visibility == "visible" )
			state = "hidden";

			document.getElementById(layer_id).style.visibility = state;
	}