can dump be tricked to overlook certain files?

[Jeff Kitson]

Is there a way I can do something to a newly created file so that dump
will not back it up (except a level 0 or under my control).  Changing
ctime for the file would seem to do the trick, but I can't find anything
on changing the ctime value for a file.

The reason for this is that we use large lisp worlds ranging from 20 to 50
megabytes.  When a new one gets created and distributed to various
machines daily backups go from a few megabytes to about 40 megabytes for
each machine.

Thanks, Jeff
jeff at kestrel.edu