::log_archive()</code> returns the names of all of the
         log files that are no longer in use (for example, that are no longer involved in active
         transactions), and that may safely be archived for catastrophic recovery and then removed
         from the system.  If there are no filenames to return, the memory location to which
         <span class="bold"><strong>listp</strong></span> refers will be set to NULL.
    </p>
      <p>
	 When Replication Manager is in use, log archiving is
	 perfor