function toggle_schedule (sSchedule, sMenuPic) {
	document.getElementById(sSchedule).style.display= (document.getElementById(sSchedule).style.display == 'none') ? 'block' : 'none';
	document.getElementById(sMenuPic).src= (document.getElementById(sMenuPic).src.indexOf('/visible_plus.gif') >= 0) ? 'images/visible_minus.gif' : 'images/visible_plus.gif';
}