@Override
 public int hashCode() {
   final int prime = 31;
   int result = 1;
   result = prime * result + ((unit == null) ? 0 : unit.hashCode());
   result = prime * result + ((value == null) ? 0 : value.hashCode());
   return result;
 }
 @Override
 public void output(StringBuffer buf) {
   value.output(buf);
   buf.append(' ');
   buf.append(unit.name());
 }