NC_CLASSIC_MODEL and nc_enddef

[wkliao]

When using flag NC_CLASSIC_MODEL to create an HDF5-based file, is calling nc_enddef() required before the first put/get var call?

In the NetCDF-C document, nc_enddef has the following statement, which implies it is not required.

It's not necessary to call nc_enddef() for netCDF-4 files.

[edwardhartnett]

Yes it is necessary when NC_CLASSIC_MODEL is used.

It is not necessary for netCDF-4 files which were created without NC_CLASSIC_MODEL.

[wkliao]

I am interested in learning the reason of why it is required. Could you please explain?

Also, look like the nc_enddef document can use a clarification.