// Checks if a string is empty
	function emptystr(string) {
		var x = 0;
		var chr;
		var empty = true;
		if (string.length) {
			do {
				chr = string.substring(x, x + 1);
				x++;
				empty = (chr == ' ' || chr == '\t' || chr == '\n' || chr == '\r');
			} while (empty && x < string.length);
		}
		return empty;
	} // function

	function showAlert(item, name) {
		if (emptystr(document.subform.elements[item].value)) {
			alert('U bent ' + name + ' vergeten in te vullen!');
			document.subform.elements[item].focus();
			return false;
		}
		else {
			return true;
		}
	} // function

	function checkEmail(item) {
		var pattern=/(^[\-_\.a-zA-Z0-9]+)@((([0-9]{1,3}\.){3}([0-9]{1,3})((:[0-9])*))|(([a-zA-Z0-9\-]+)(\.[a-zA-Z]{2,})+(\.[a-zA-Z]{2})?((:[0-9])*)))/;
		if (document.subform.elements[item].value.search(pattern) == -1) {
			alert('Dit is geen geldig e-mail adres!');
			document.subform.elements[item].focus();
			return false;
		}
		else	{
			return true;
		}
	} // function

	function checkForm() {
		return (
			showAlert('achternaam', 'uw achternaam') &&
			showAlert('voornaam','uw voornaam') &&
			showAlert('email','uw e-mail adres') &&
			checkEmail('email')
		);
	} // function
	
	function MM_preloadImages() { //v3.0
	  var d=document; if(d.images){ if(!d.MM_p) d.MM_p=new Array();
		var i,j=d.MM_p.length,a=MM_preloadImages.arguments; for(i=0; i<a.length; i++)
		if (a[i].indexOf("#")!=0){ d.MM_p[j]=new Image; d.MM_p[j++].src=a[i];}}
	}
	
	function MM_swapImgRestore() { //v3.0
	  var i,x,a=document.MM_sr; for(i=0;a&&i<a.length&&(x=a[i])&&x.oSrc;i++) x.src=x.oSrc;
	}
	
	function MM_findObj(n, d) { //v4.01
	  var p,i,x;  if(!d) d=document; if((p=n.indexOf("?"))>0&&parent.frames.length) {
		d=parent.frames[n.substring(p+1)].document; n=n.substring(0,p);}
	  if(!(x=d[n])&&d.all) x=d.all[n]; for (i=0;!x&&i<d.forms.length;i++) x=d.forms[i][n];
	  for(i=0;!x&&d.layers&&i<d.layers.length;i++) x=MM_findObj(n,d.layers[i].document);
	  if(!x && d.getElementById) x=d.getElementById(n); return x;
	}
	
	function MM_swapImage() { //v3.0
	  var i,j=0,x,a=MM_swapImage.arguments; document.MM_sr=new Array; for(i=0;i<(a.length-2);i+=3)
	   if ((x=MM_findObj(a[i]))!=null){document.MM_sr[j++]=x; if(!x.oSrc) x.oSrc=x.src; x.src=a[i+2];}
	}