function show(nav) {
	if(document.getElementById) {
		document.getElementById(nav).style.visibility = "visible";
	}
}

function hide(nav) {
	if(document.getElementById) {
		document.getElementById(nav).style.visibility = "hidden";
	}
}

function hideall() {
	if(document.getElementById) {
		document.getElementById("nav_01").style.visibility = "hidden";
		document.getElementById("nav_02").style.visibility = "hidden";
		document.getElementById("nav_03").style.visibility = "hidden";
		document.getElementById("nav_04").style.visibility = "hidden";
		document.getElementById("nav_05").style.visibility = "hidden";
		document.getElementById("nav_06").style.visibility = "hidden";
	}
}