@Override
 public String toString() {
   StringBuffer buf = new StringBuffer();
   if (entry_transaction != null && getEntryTransaction() != entry_task) {
     buf.append(getEntryTransaction().toString());
     buf.append("::");
   }
   if (entry_task != null) {
     buf.append(entry_task.toString());
   }
   buf.append("@");
   buf.append(start_time);
   if (finish_time != 0 && finish_time != MAX_TIME) {
     buf.append("-");
     buf.append(finish_time);
   }
   return buf.toString();
 }