My thanks to everyone for the great advice.  Your response, Suzanne,
confirmed another problem that was just beginning to dawn on me.  Reversing
the temporary number to create the accession number doesn't work when
something comes in during 2002 but doesn't get accessioned until 2003.  I'm
now going to be left with gaps in the year 2002 accession records, wish I'd
asked this question a year ago!
 
Anne