function mkSelect(nm, st, en, stp) {
      document.write('<select name="'+nm+'">');
      if (st <= en) {
        for (var i=st;i<=en;i=i+stp)
          document.write('<option value="'+i+'">'+i+'</option>');
      } else {
        for (var i=st;i>=en;i=i+stp)
          document.write('<option value="'+i+'">'+i+'</option>');
      }
      document.write('</select>');
    }

    function isNull(n, msg) {
      if ((n.value == null) || (n.value == "")) {
        if (msg != null) alert(msg);
        return true;
      }
      return false;
    }


function isEmpty(s) {
  return ((s == undefined) || (s == null) || (s == ""));
}