CDF_SET_CDF27_BACKWARD_COMPATIBLE
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The CDF_SET_CDF27_BACKWARD_COMPATIBLE function allows users to create a 
CDF file that can be read by IDL 6.2 (or earlier IDL versions) or CDF 2.7.2 
(or earlier CDF versions).  By default, a CDF file created by IDL 6.3 
(which uses CDF 3.1) or CDF 3.0 or a later release can't be read by CDF 
library that's older than 3.0 (e.g. IDL 6.2, CDF 2.7.x, 2.6.x, 2.5.x, etc.).

This new routine is for users who wish to create and share CDF files 
with colleagues who access CDF files using IDL 6.2 (or earlier version) or 
a CDF library that's older than 3.0 (e.g. 2.7.x, 2.6.x, 2.5.x, etc.)
This routine must be called prior to calling the CDF_CREATE routine.

Note that up until CDF 2.7.2, the maximum CDF file size was 2 Gbytes and 
this limitation was lifted in CDF 3.0 with the use of 64-bit file offset.  
As a result, users who use a CDF library older than CDF 3.0 can't read 
CDF files that were produced by CDF 3.0 or a later release.  But CDF 3.0 or 
a later release can read files that were generated with any of the previous 
CDF releases.


Syntax 
CDF_SET_CDF27_BACKWARD_COMPATIBLE, /YES | /NO


Keywords           
YES                Create a CDF file that can be read by IDL 6.2 (or earlier 
                   IDL versions) or CDF 2.7.2 (or earlier CDF releases).  
                   If this option is set, the maximum file size is 2 Gbytes.

NO                 This is the default when a CDF file is created. 


Examples 
Use the following command to create a CDF file that can be read by IDL 6.2
or earlier IDL versions.

CDF_SET_CDF27_BACKWARD_COMPATIBLE, /YES
id = CDF_CREATE('myfile.cdf')
CDF_CLOSE, id


Version History 
Introduced: IDL 6.3