function validate(form)
{

  //possible regular expressions
  var formats 		   = new Array();
  formats['nummer']	   = "^\d+$";
  formats['email adres'] = "^[\_]*([a-z0-9]+(\.|\_*)?)+@([a-z][a-z0-9\-]+(\.|\-*\.))+[a-z]{2,6}$";

  message = "";
  for(i=0;i < form.elements.length;i++)  
  {
      if ( (form.elements[i].name) && (form.elements[i].id) )
        {
	    e = form.elements[i];
	    if (e.id == "notnull")
            {		
	    	if (!e.value) message += e.name.toString() + ' moet ingevuld worden\n'; 
	    }
	    else if (e.id == "nummer")
	    {
		if (isNaN(e.value)) message += "'" + e.value + "' is geen getal\n";
            }
            else  
            {
		if ( !e.value.match(formats[e.id]) ) message += "'" + e.value + "' is geen geldig(e) " + e.id + "\n";
            }
	}
  }

  if (message.toString().length > 0)
  {
  	alert(message);
	return false;
  }
  else return true; 


}



function change_language(language)
{
    document.location = '?changeto=' + language + '&redirect=' + document.location;
}

function openWindow(image) 
{ 

  var winl = (screen.width - w) / 2; 
  var wint = (screen.height - h) / 2; 

    var h = 500; 
    var w = 500;

  winprops =  'height=' +h+ ',width=' +w+ ',menubar=0,resizable=0,scrollbars=0,status=0,titlebar=0,toolbar=0,left=' + winl + ',top=' + wint;

  window.open('img/'+image,"",winprops);
}