function dateCheck(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 19xx */
	 if (DateValue.length == 6) {
	    DateValue = '19' + DateValue; }
	 if (DateValue.length != 8) {
	    err = 19;}
	 /* year is wrong if year = 0000 */
	 year = DateValue.substr(0,4);
	 if (year == 0) {
	    err = 20;
	 }
	 /* Validation of month*/
	 month = DateValue.substr(4,2);
	 if ((month < 1) || (month > 12)) {
	    err = 21;
	 }
	 /* Validation of day*/
	 day = DateValue.substr(6,2);
	 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 = 1; day = ""; month = ""; year = ""; seperator = "";
	 }
	 /* if no error, write the completed date to Input-Field (e.g. 13.12.2001) */
	 if (err == 0) {
	    return year + seperator + month + seperator + day;
	    //return true;
	 }
	 /* Error-message if err != 0 */
	 else {
	    return false;
	 }
}