function limiet(veld, maximum, telveld)
{
   if (veld.value.length > maximum)
      veld.value = veld.value.substring(0, maximum);
   else
      document.getElementById(telveld).firstChild.nodeValue = (maximum - veld.value.length);
}

function popup(page,title,width,height)
{
	var winl = (screen.width - width) / 2;
    var wint = (screen.height - height) / 2;

   	window.open(''+page,''+title,'width='+width+',height='+height+',top='+wint+',left='+winl+',resizable=no,scrollbars=no,toolbar=no');
}