ferret -batch vs Fprint

[Peter Rayner <pjr@xxxxxxxxxxxxxxxxxxxxxxxx>]

Hi, I've got a follow-up question to last week's one on producing
hardcopy without X.  I'm now doing this but there *seems* to be a
problem.  
When running ferret (V4.91 on Irix) as ferret 
the behaiviour seems different depending on whether  I'm running with
-batch or not.
Without -batch hardcopy produced with set mode metafile seems fine.
With -batch on what I fervently hope is the same plotting script I get
reports from Fprint like
Fprint -o out.ps metafile.plt
GKSM item 3 is undefined
GKSM item 3 is undefined

and a postscript file which won't print.  
This doesn't seem to depend on whether I use 
set mode metafile
within ferret or not (I don't need to right?).
I presume I'm doing something wrong here, any guidance?
Peter Rayner