>The one thing you haven't covered is what happens after "FFFFFFF". Do you start over? How fast will you get there? Will you archive the first batches so you won't have key problems?


THhe on oft this seroies seems to be "ZZZZZZZ" and not "FFFFFFF" since we are not in base16 but in base26 here.
I would just keep a table of NonAllow words (I would call FourLtrWrds.DBF :-)
and check that rather than storw billions and billions (taht sounds like Carl Sagan) of records.

Peter