function check_date(field){
var checkstr = "0123456789";
var DateField = field;
var Datevalue = "";
var DateTemp = "";
var seperator = "/";
var day;
var month;
var year;
var leap = 0;
var err = 0;
var i;
   err = 0;
   DateValue = DateField.value;
   var date_array = DateValue.split(seperator);
         
   /* year is wrong if year = 0000 */
   year = date_array[2];
   if (year == 0) {
      err = 20;
   }
   /* Validation of month*/
   month = date_array[0];
   if ((month < 1) || (month > 12)) {
      err = 21;
   }

   /* Validation of day*/
   day = date_array[1];
   if (day < 1) {
     err = 22;
   }
   
   
   /* Validation leap-year / february / day */
   if ((year % 4 == 0) || (year % 100 == 0) || (year % 400 == 0)) {
      leap = 1;
   }
   if ((month == 2) && (leap == 1) && (day > 29)) {
      err = 23;
   }
   if ((month == 2) && (leap != 1) && (day > 28)) {
      err = 24;
   }
   /* Validation of other months */
   if ((day > 31) && ((month == "01") || (month == "03") || (month == "05") || (month == "07") || (month == "08") || (month == "10") || (month == "12"))) {
      err = 25;
   }
   if ((day > 30) && ((month == "04") || (month == "06") || (month == "09") || (month == "11"))) {
      err = 26;
   }
   /* if 00 ist entered, no error, deleting the entry */
   if ((day == 0) && (month == 0) && (year == 00)) {
      err = 0; day = ""; month = ""; year = ""; seperator = "";
   }
   /* if no error, write the completed date to Input-Field (e.g. 13.12.2001) */
   if (err == 0) {
      DateField.value = month + seperator + day + seperator + year;
   }
   /* Error-message if err != 0 */
   else {
      alert("Date is incorrect!");
      DateField.select();
	  DateField.focus();
   }
}
//  End -->