function CheckRequiredFields() {
var errormessage = new String();
if(WithoutContent(document.form1.Voornaam.value))	{errormessage += "\n\nvul hier uw Voornaam in";}
if(WithoutContent(document.form1.Achternaam.value))	{errormessage += "\n\nvul hier uw Achternaam in";}
if(WithoutContent(document.form1.Email1.value))	{errormessage += "\n\nvul hier uw E-mailadres in";}
if(WithoutContent(document.form1.Straatnaam.value))	{errormessage += "\n\nvul hier uw Straatnaam in";}
if(WithoutContent(document.form1.Postcode.value))	{errormessage += "\n\nvul hier uw Postcode in";}
if(WithoutContent(document.form1.Woonplaats.value))	{errormessage += "\n\nvul hier uw Woonplaats in";}


if(errormessage.length > 2) {
	alert('NOTE:' + errormessage);
	return false;
	}
return true;
} 

function WithoutContent(ss) {
if(ss.length > 0) { return false; }
return true;
}

function NoneWithContent(ss) {
for(var i = 0; i < ss.length; i++) {
	if(ss[i].value.length > 0) { return false; }
	}
return true;
}

function NoneWithCheck(ss) {
for(var i = 0; i < ss.length; i++) {
	if(ss[i].checked) { return false; }
	}
return true;
}

function WithoutCheck(ss) {
if(ss.checked) { return false; }
return true;
}

function WithoutSelectionValue(ss) {
for(var i = 0; i < ss.length; i++) {
	if(ss[i].selected) {
		if(ss[i].value.length) { return false; }
		}
	}
return true;
}