It's been quite a while since i've done this but as I recall the IFILE should
be
an integer variable and  it's value corresponds to the appropriate entry in
the
fortran logical unit number table.    The @I is requesting a directed
(relative)
read to a specific record number.   If I recall you need to  issue a file
equation similar to "FILE FTNnn=FILENAME" where nn equals the content
of the IFILE variable in the program.

Bob