var isNN = (navigator.appName.indexOf("Netscape") != -1);

       function autoTab(input, len, e) {
           var keyCode = (isNN) ? e.which : e.keyCode;
           var filter = (isNN) ? [0, 8, 9] : [0, 8, 9, 16, 17, 18, 37, 38, 39, 40, 46];

           if (input.value.length >= len && !containsElement(filter, keyCode)) {
               input.value = input.value.slice(0, len);
               input.form[(getIndex(input) + 1) % input.form.length].focus();
           }

           function containsElement(arr, ele) {
               var found = false, index = 0;
               while (!found && index < arr.length)
                   if (arr[index] == ele) found = true;
               else index++;
               return found;
           }

           function getIndex(input) {
               var index = -1, i = 0, found = false;
               while (i < input.form.length && index == -1)
                   if (input.form[i] == input) index = i;
               else i++;
               return index;
           }
           return true;
       }
       function checkDigit(e) {
           var keynum
           var keychar
           var numberRegex

           if (window.event) { // IE
               keynum = e.keyCode
           } else if (e.which) { // Netscape/Firefox/Opera
               keynum = e.which
           }
           //alert("keynum " +keynum +"\n" + "keychar " + keychar);
           return ((keynum >= 96 && keynum <= 105) || (keynum >= 48 && keynum <= 57) || (keynum == 8 || keynum == 46 || keynum == 177 || keynum == 110));
       }