clearing logical logs

Is it safe to clear logical logs after a successful dbexport of all databases maintained by a OnLine system? Assume that the dbexported stuff is all I am ever gonna need and I won't wanna go back to any image before it and that the dbexported stuff is absolutely safe (no risk of losing it, even in the event of Earth destruction). If it is, how do I do it? I could do it (well, almost) by backing up the logical logs to /dev/null. But: 1. tbtape -a didn't wanna backup non-full logs at my 1st attempt. When tried again, it did. But some tail (a tiny bit) was left behind. What's the story? It looked like tbtape recorded the backup event itself in the logs. 2. I tried performing a level 0 archive but the logs wouldn't go away (I think Informix reckoned that some trx may need to be rolled back - even if there actually weren't any - and therefore didn't clear the logs). So is it silly or smart if Informix clears the logs for you - after a level 0 archive AND - there's no active transactions - all have either been committed or rolled back (that would be the case if the system is in quiescent mode right?)