// JavaScript Document

function showSubMenu(menu_number) {
	
	// please update if sub menu number changes
	var total_sub_menus = 3;
	
	var i = 1;
	
	// hide all sub menus
	while (i <= total_sub_menus) {
		document.getElementById("sub_menu_"+i).style.display = 'none';
		i = i+1;
	}
	
	// display requested sub menu
	if (menu_number != 'none') {	
		document.getElementById("sub_menu_"+menu_number).style.display = 'block';
	}
	
}