function empty_form(form)
{
    for (var i = 0; i<form.elements.length; i++) 
	{
        if ((form.elements[i].type.indexOf('text') > -1)) 
		{
            form.elements[i].value ='';
        }
        if ((form.elements[i].type.indexOf('checkbox') > -1)) 
		{
            form.elements[i].value =false;
        }
    }
	form['invia'].value = 'cancella';
	form.submit();
}