function validate_course(f){
	required=new Array("course","salutation","firstname","surname","company","jobtitle","tel","email");
	for(i=0;i<required.length;i++){
		o=eval("f."+required[i]);
		if(o.value==""){
			alert("Please fill in empty field");
			//if(o.type=="select-multiple" || o.type=="select-one"){o.focus()}else{o.select()}
			o.focus();
			return false;
		}
	}
	if(f.email.value.search(/\w+[^.][@][^.]\w+[.]\w+/)<0 || f.email.value==""){
		alert("Please enter a correct mail address");
		f.email.select();
		return false;
	}
	if(document.getElementById('paymentdiv').style.display!="none"){
		if(!f.payment[0].checked && !f.payment[1].checked){
			alert("Please select a form of payment");
			f.payment[0].focus;
			return false;
		}
		if(f.payment[1].checked && f.billaddr1.value==""){
			alert("Please enter your billing details");
			f.billaddr1.focus();
			return false;
		}
	}
	if(!f.user_code.value){
		f.user_code.focus();
		alert("Please enter the visual confirmation code.");
		return false;
	}
	return true;
}