function ShowDate(date_form, date_field) {
         url='mc_calendar.asp?date_form=' + date_form + '&date_field=' + date_field;
	window.open(url,"_blank","height=200,width=390, resizable=yes");
	
}
 
function isDate(dateStr) {

	var datePat = /^(\d{1,2})(\/|-)(\d{1,2})(\/|-)(\d{4})$/;
	var matchArray = dateStr.match(datePat); // is the format ok?
	
	if (matchArray == null) {
		alert("La data deve essere nel formato gg/mm/aaaa");
		return false;
	}
	
	month = matchArray[3]; // p@rse date into variables
	day = matchArray[1];
	year = matchArray[5];

	if (month < 1 || month > 12) { // check month range
		return false;
	}
	
	if (day < 1 || day > 31) {		
		return false;
	}
	
	if ((month==4 || month==6 || month==9 || month==11) && day==31) {	
		return false;
	}
	
	if (month == 2) { // check for february 29th
		var isleap = (year % 4 == 0 && (year % 100 != 0 || year % 400 == 0));
		if (day > 29 || (day==29 && !isleap)) {		
			return false;
		}
	}
	return true; // date is valid
}