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_validateForm() { //v4.0
  var i,p,q,nm,test,num,min,max,errors='',args=document.validationElms?document.validationElms:MM_validateForm.arguments;
  for (i=0; i<(args.length-2); i+=3) { test=args[i+2]; val=MM_findObj(args[i]);
    if (val) { nm=val.name; if ((val=val.value)!="") {
      if (test.indexOf('isEmail')!=-1) { p=val.indexOf('@');
        if (p<1 || p==(val.length-1)) errors+='- '+nm+' must contain an e-mail address.\n';
      } else if (test!='R') { num = parseFloat(val);
        if (isNaN(val)) errors+='- '+nm+' must contain a number.\n';
        if (test.indexOf('inRange') != -1) { p=test.indexOf(':');
          min=test.substring(8,p); max=test.substring(p+1);
          if (num<min || max<num) errors+='- '+nm+' must contain a number between '+min+' and '+max+'.\n';
    } } } else if (test.charAt(0) == 'R') errors += '- '+nm+' is vereist.\n'; }
  } if (errors) alert('De volgende velden zijn niet (juist) ingevuld:\n'+errors);
  document.MM_returnValue = (errors == '');
}

function uncheck()
{
	if (document.contact.geenemail.checked ==  true)
	{
		document.contact.geenemail.checked = false;
	}
}

function geenEmailOpt(mode)
{
	target = document.getElementById("geenEmail");
	if (mode !== "show")
	{
		target.style.visibility = "hidden";
		uncheck();
	}
	else 
	{
		target.style.visibility = "visible";
	}
}

function updateFormValidationRequirements( field ) {
	switch( field ) {
		case 'tel': 		document.validationElms = ['naam','','R','telnr','','RisNum']; geenEmailOpt("show"); break;
		case 'fax': 		document.validationElms = ['naam','','R','faxnr','','RisNum']; geenEmailOpt("show"); break;
		case 'email': 	document.validationElms = ['naam','','R','email','','RisEmail']; geenEmailOpt(); break; 
		case 'post': 	document.validationElms = ['naam','','R','adres','','R','postcode','','R','woonplaats','','R','land','','R']; geenEmailOpt("show"); break;
		default: 			document.validationElms = ['naam','','R']; geenEmailOpt("hide"); break; 
	}
}