Event.observe(window, 'load', get_merk, false);
	
	function get_merk(){
		var url = '/vdh/get_merk.php';
		var pars = 'merk='+escape($F('merk'))+'&model='+escape($F('post_model'));
		var target = 'a_model';
		var myAjax = new Ajax.Updater(target, url, { method: 'get', parameters: pars });
	}