Question about nccopy

[jedwards4b]

I'm trying to follow the flow of nccopy.c and I have a question about this call to
count_dims
It's called with igrp which is the ncid of the file opened to read. In count_dims we have a
call to nc_inq_grps
My question is why can nccopy call this when the input file is in a netcdf3 format and not get a NC_ENOTNC4
error?

[DennisHeimbigner]

Where possible, we try to define the netcdfd-4 API functions for netcdf-3: see libsrc/nc3dispatch.c.
In this case, a netcdf-3 file is treated as if it has a single root group and no subgroups.

[jedwards4b]

thanks