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;
   /* Delete all chars except 0..9 */
   for (i = 0; i < DateValue.length; i++) {
	  if (checkstr.indexOf(DateValue.substr(i,1)) >= 0) {
	     DateTemp = DateTemp + DateValue.substr(i,1);
	  }
   }
   DateValue = DateTemp;
   
   /* Always change date to 8 digits - string*/
   /* if year is entered as 2-digit / always assume 20xx */
   if (DateValue.length == 6) {
      DateValue = DateValue.substr(0,4) + '20' + DateValue.substr(4,2);
   }
   if (DateValue.length != 8) {
      err = 19;
   }
   /* year is wrong if year = 0000 */
   year = DateValue.substr(4,4);
   /*
   if (year == 0) {
      err = 20;
   }
   */
   /* Validation of month*/
   month = DateValue.substr(2,2);
   if (month > 12) {
      err = 21;
   }
   /* Validation of day*/
   day = DateValue.substr(0,2);
   if (day > 31) {
     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 is entered, error, set to 00-00-0000 */
   if ((day == 0) && (month == 0) && (year == 00)) {
      DateField.value = '00-00-0000';
   }
   /* if no error, write the completed date to Input-Field (e.g. 13-12-2001) */
   if (err == 0) {
      err = 100;
      DateField.value = day + seperator + month + seperator + year;
   }
   /* Error-message if err != 0 */
   else {
      alert('Datum is niet correct!\r\n\r\nIk zet de datum op 00-00-0000.');
      DateField.value = "00-00-0000";
      DateField.select();
      DateField.focus();
   }
}


/* validate time */
function check_time(field) {
var checkstr = "0123456789";
var TimeField = field;
var Timevalue = "";
var TimeTemp = "";
var seperator = ":";
var hour;
var minute;
var second;
var leap = 0;
var err = 0;
var i;
   err = 0;
   TimeValue = TimeField.value;
   /* Delete all chars except 0..9 */
   for (i = 0; i < TimeValue.length; i++) {
	  if (checkstr.indexOf(TimeValue.substr(i,1)) >= 0) {
	     TimeTemp = TimeTemp + TimeValue.substr(i,1);
	  }
   }
   TimeValue = TimeTemp;
   
   if (TimeValue.length != 4) {
      err = 19;
   }
   minute = TimeValue.substr(2,2);
   if (minute > 60) {
      err = 21;
   }
   hour = TimeValue.substr(0,2);
   if (hour > 24) {
     err = 22;
   }

   /* if 00 is entered, error, set to 00:00:00 */
   if ((hour == 00) && (minute == 00)) {
      TimeField.value = '00:00';
   }
   /* if no error, write the completed time to Input-Field (e.g. 12:60) */
   if (err == 0) {
      err = 100;
      TimeField.value = hour + seperator + minute;
   }
   /* Error-message if err != 0 */
   else {
      alert('tijd is niet correct!\r\n\r\nIk zet de lengte op 00:00.');
      TimeField.value = "00:00";
      TimeField.select();
      TimeField.focus();
   }
}