OPENW using /XDR (IDL 5.1/linux) WARNING!

["Russ Welti (on mapper)" <rwelti(at)mapper.mbt.washington.edu>]

The 5.1 online help for OPENW states that /XDR option is
basically obsolete but does NO harm to be present
(for backward compatibility).
 
But I finally found my problem in porting a huge IDL
application from my Solaris 5.0 IDL workstation
to my test linux box, and it was definitely due to
the presence of the /XDR on an OPENW statement.
 
I presume this is a bug, if it is not, i would very much
appreciate being contacted to tell me otherwise, so i
can maintain my IDL source code properly (i.e. single
copy of the source code, not both a 5.0 and a 5.1+ version)

Below, i have included a tiny example session where
the error is displayed.

IDL> print,path
/home/saga/geno/rwelti/ceph/C30-3AH/
IDL>  openw,unit,path+"/tst.bin",/get_lun,/XDR 
IDL> writeu,unit,float(1.0)
IDL> free_lun,unit
IDL> r=float(0.0)
IDL> openr,unit,path+"/tst.bin",/get_lun
IDL> readu,unit,a
IDL> help,a
A               FLOAT     =   4.60060e-41
% Program caused arithmetic error: Floating underflow
 
IDL> free_lun,unit
IDL> openw,unit,path+"/tst.bin",/get_lun      <== NO /XDR here
IDL> writeu,unit,float(1.0)
IDL> free_lun,unit
IDL> r=float(0.0)
IDL> openr,unit,path+"/tst.bin",/get_lun
IDL> readu,unit,a
IDL> help,a
A               FLOAT     =       1.00000


Sincerely,
                                                    /
Russ Welti                                         /-\
                                                  (c-g)                     
University of Washington                           \-/                      
Molecular Biotechnology                             /                       
PO Box 357730                                      /-\                      
Seattle, WA  98195                                (a-t)                     
rwelti@u.washington.edu                            \-/                     
(206) 616 5116 voice   (206) 685 7301 FAX           /