Problem restoring IDL SAVE files in version 5.3 when created in version 5.4

["Christopher K. Pankratz" <chris.pankratz(at)lasp.colorado.edu>]

I are attempting to save a variable created in an IDL 5.4 session for
someone to restore in IDL 5.3, and I are running into some problems.  Here
is a sample session for creating the save file in IDL 5.4 and restoring it
in IDL 5.3 which illustrates the problem.

In IDL 5.4:
IDL> rec = {a:0.0, b:0L, c:bytarr(200)}
IDL> save, rec, file='test.sav'

In IDL 5.3:
IDL> restore, 'test.sav'
% RESTORE: Unexpected item code found in save file.
% RESTORE: Unexpected item code found in save file.
% RESTORE: Unexpected item code found in save file.
% RESTORE: Unexpected item code found in save file.
% RESTORE: Unexpected item code found in save file.
% RESTORE: Unexpected item code found in save file.
% RESTORE: Unexpected item code found in save file.
% RESTORE: Unexpected item code found in save file.
% RESTORE: Unexpected item code found in save file.
% RESTORE: Unexpected item code found in save file.
% RESTORE: Unexpected item code found in save file.
% RESTORE: Unexpected item code found in save file.
% RESTORE: Unexpected item code found in save file.
% RESTORE: Unexpected item code found in save file.
% RESTORE: Unexpected item code found in save file.
% RESTORE: Unexpected item code found in save file.
% RESTORE: Unexpected item code found in save file.
% RESTORE: Unexpected item code found in save file.
% RESTORE: Unexpected item code found in save file.
% RESTORE: Unexpected item code found in save file.
% RESTORE: Unexpected item code found in save file.
% RESTORE: Unexpected item code found in save file.
% RESTORE: Unexpected item code found in save file.
% RESTORE: Unexpected item code found in save file.
% RESTORE: Unexpected item code found in save file.
% RESTORE: Unexpected item code found in save file.
% RESTORE: Unexpected item code found in save file.
% RESTORE: Unexpected item code found in save file.
% RESTORE: Unexpected item code found in save file.
% RESTORE: Unexpected item code found in save file.
% RESTORE: Unexpected item code found in save file.
% Execution halted at:  $MAIN$

The IDL 5.4 reference manual indicates that saving/restoring data should be
backward compatible.  It says "Note also that save files containing routines
may not be compatible between different versions of IDL, but that files
containing data are always backwards-compatible."  It is my intent not to
store any information other than the variable of interest, which does happen
to be a structure.

I have tried using the "/VARIABLES" keyword to the SAVE command as well, but
this does not seem to help.  Any assistance would be appreciated.

Thanks,
Chris