function checkFrame() {
	if (parent.frames.length==0) 
		top.location='index.html';
}

function tarief(tarief_option) {
	var t = tarief_option.split(';');
					
	document.tarieven.vast_tarief.value = t[1];
	document.tarieven.vast_telefoon.value = t[2];			
}

var mnu;
var tmnu;

function menu() {
	mnu  = document.all('tab_menu');
	tmnu = document.all('tab');
}

function showMenu(m) {
	for (i = 0; i < mnu.length; i++)
		if (mnu[i].name == m) 
			mnu[i].style.display = '';
		else
			mnu[i].style.display = 'none';		

	
	for (i = 0; i < tmnu.length; i++)
		if (tmnu[i].name == m) 
			tmnu[i].className = 'menu';
		else
			tmnu[i].className = 'bmenu';
}