function check_form(formtype)
{
	var bool = true;
	
	switch(formtype)
	{
		case 1:
		required = new Array("Naam", "Functie", "Instelling", "E-mail", "Adres", "Postcode", "Plaats", "Telefoonnummer");
		break;
		
		case 2:
		required = new Array("Naam", "Functie", "Instelling", "E-mail", "Adres", "Postcode", "Plaats", "Telefoonnummer");
		break;
		
		case 3:
		required = new Array("Naam", "Functie", "Instelling", "E-mail", "Adres", "Postcode", "Plaats", "Telefoonnummer");
		break;
		
		case 4:
		required = new Array("Naam", "Geboorte_datum", "Adres", "Postcode", "Plaats", "Certificaat_behaald_op", "Registratienummer", "In_de_instelling");
		break;
		
		case 5:
		required = new Array("Naam", "Prive_adres", "Postcode", "Plaats", "E-mail", "Telefoonnummer_", "Faxnummer_");
		break;
		
		case 6:
		required = new Array("Naam", "Prive_adres", "Postcode", "Plaats", "E-mail", "Telefoonnummer", "Faxnummer");
		break;
		
		// case 7 is an exception
		
		case 8:
		required = new Array("Instelling", "Contactpersoon", "Functie", "Adres", "Postcode_en_plaats", "E-mail", "Telefoon", "Doelgroep", "Cursusdata", "Aantal_cursisten");
		break;
		
		case 9:
		required = new Array("Ontvanger", "Afzender");
		break;
		
		case 10:
		required = new Array("Aantal_Reader_Deel_I", "Aantal_Reader_Deel_II", "Contactpersoon", "Instelling", "Verzend_adres", "Postcode", "Plaats", "Telefoonnummer", "Datum_aanvang_training");
		break;
		
		case 11:
		required = new Array("Contactpersoon", "Instelling", "Verzend_adres", "Postcode", "Plaats", "Telefoonnummer", "Datum_bijscholingsdag");
		break;
		
	}

	for (var i =0; i<required.length; i++)
	{
		
		var r = required[i];
		var cur = document.formulier[r].value;
		
		if (cur == "")
		{
			bool = false;
		}
	}

	if(bool == false)
	{
		alert("Niet alle verplichte velden zijn ingevuld.");
	} 
	else
	{
		document.formulier.submit();
	}
}