'Defing' filenames

[spotter at desire.wright.edu]

I need to know how to define a file as one of the fort.# files without
renaming the file.  On VMS there is a command (define) that will allow a user
to define 'filea' as 'for###' for purposes of a fortran program to read and
write (used without opening and closing the file), and I need to know how to do
it on UNIX.  

Please email responses to me, as I haven't received any new news for two days
and think there must be some sort of problem somewhere.

Stephen Potter
spotter at desire.wright.edu