//list of required fields
list = new Array (0,1,2,3,8,9,13,14,15);

//fields checker
function checker(field_number)
	{
	empty_field=NaN;
	form_element=document.forms['mainform'].elements[field_number];
	if (form_element.type=='text') if (!form_element.value) empty_field=field_number;
	if (form_element.type=='select-one') if (!form_element.options[form_element.options.selectedIndex].value) empty_field=field_number;
	return empty_field;
	}
	
//form checker
function gonext()
	{
	field_number=-1;
	for (i=list.length-1; i>=0; i--)
		{
		if (!isNaN(checker(list[i]))) field_number=list[i]
		};
	if (field_number!=-1)
		{
		field=document.forms['mainform'].elements[field_number];
		alert("Impossibile proseguire. Un campo richiesto e vuoto, oppure incorretto. Si prega di correggere i campi evidenziati");
		field.focus();
		if (field.type!='select-one') field.select();
		}
	else
		{
		document.forms['mainform'].action="http://quickfield.com/scripts/download.php";
		document.forms['mainform'].submit()
		};
	}