Ferret & CDF missing values

[<simon@xxxxxxxxxxxxxxxxx>]

    Dear Ferret users,

    I have a fortran program that assigns special values to missing
 data. I tell the CDF file about them via calls like

    call NCAPT(CDFID,variable_id,'missing_value',NCDOUBLE,1,FVAL,IRET),

    where FVAL = -99999.0. Just for good measure, I make a similar
 assignment to _FillValue also. I know that the CDF file has taken
 the information on board, since ncdump -h reports missing_value and
 _FillValue correctly.

    However, in Ferret v4.9, the missing values aren't recognized. For
 example,

yes? stat z1
 
             Method 1
             X (mm): -7.6 to 7.6
             Y (mm): -7.6 to 7.6
             Z: 0.5 to 6.5
             T:  N/A
             DATA SET: ./lens.cdf
 
 Total # of data points: 60000 (100*100*6*1)
 # flagged as bad  data: 0
 Minimum value: -99999
 Maximum value: 1

   
   I must admit that it's been a year or so since I've used Ferret,
 but I swear it used to work! I can, of course, get around it using
 set variable/bad, but that's non-transparent. It really ought to
 be able to be set automatically through the CDF file, right?

   Regards,

=================================================================
Simon Evans (simon@maths.unsw.edu.au)
Physical Oceanography Group
School of Mathematics, University of New South Wales, Australia.
=================================================================