function CheckFieldLength(fn,wn,rn,mc) {
// fieldname, warningname, remainingname, maxchars
  var len = fn.value.length;
  if (len > mc) {
    fn.value = fn.value.substring(0,mc);
    len = mc;
  }
  document.getElementById(wn).innerHTML = len;
  document.getElementById(rn).innerHTML = mc - len;
}

function CheckFieldLength(fn, rn,mc) {
//this returns only X number of characters remaining
  var len = fn.value.length;
  if (len > mc) {
    fn.value = fn.value.substring(0,mc);
    len = mc;
  }
  document.getElementById(rn).innerHTML = mc - len;
}

function CheckFieldLength(fn, mc) {
//this returns no warning. Simply works like maxlength.
  var len = fn.value.length;
  if (len > mc) {
    fn.value = fn.value.substring(0,mc);
    len = mc;
  }
}