Typo in mac-file-io.lisp?

["Dave Wroblewski" <davew@atqm.advtech.uswest.com>]

                      Typo in mac-file-io.lisp?
I was trying to work through Bill St. Clair's "my-copy-file" example today in
order
to understand the mac-file-io.lisp code in the Examples folder. Unhappily, it
kept
bombing with error -50 ("parameter error"). 

I found the following lines in the middle of the function FSOpen in
mac-file-io.lisp:

              (%put-long paramBlock 0  $ioPosOffset)
              (%put-word paramBlock $fsAtMark $ioPosOffset)
  
which seemed incorrect, since they simply set the same field to different
values.
I changed them to the following which seems to remove the problem, at least for
Bill's example function:

              (%put-long paramBlock 0 $ioPosOffset)
              (%put-word paramBlock $fsAtMark $ioPosMode)

Was this truly a typo, or is there some incredible subtlety that I am missing?
Also, if this was a known bug, where should I have looked to find it out? I
have 
been reading this mailing list for a month or two and haven't seen any bug
reports
about this...

-David Wroblewski
U S WEST Advanced Technologies