netCDF 4.2.1.1
Examples

By using the grammar above, we can derive the smallest valid netCDF file, having no dimensions, no variables, no attributes, and hence, no data.

A CDL representation of the empty netCDF file is

netcdf empty { }

This empty netCDF file has 32 bytes. It begins with the four-byte “magic number” that identifies it as a netCDF version 1 file: ‘C’, ‘D’, ‘F’, ‘\x01’. Following are seven 32-bit integer zeros representing the number of records, an empty list of dimensions, an empty list of global attributes, and an empty list of variables.

Below is an (edited) dump of the file produced using the Unix command

od -xcs empty.nc

Each 16-byte portion of the file is displayed with 4 lines. The first line displays the bytes in hexadecimal. The second line displays the bytes as characters. The third line displays each group of two bytes interpreted as a signed 16-bit integer. The fourth line (added by human) presents the interpretation of the bytes in terms of netCDF components and values.

        4344    4601    0000    0000    0000    0000    0000    0000
       C   D   F 001  \0  \0  \0  \0  \0  \0  \0  \0  \0  \0  \0  \0
       17220   17921   00000   00000   00000   00000   00000   00000
     [magic number ] [  0 records  ] [  0 dimensions   (ABSENT)    ]
     
        0000    0000    0000    0000    0000    0000    0000    0000
      \0  \0  \0  \0  \0  \0  \0  \0  \0  \0  \0  \0  \0  \0  \0  \0
       00000   00000   00000   00000   00000   00000   00000   00000
     [  0 global atts  (ABSENT)    ] [  0 variables    (ABSENT)    ]

As a less trivial example, consider the CDL

     netcdf tiny {
     dimensions:
             dim = 5;
     variables:
             short vx(dim);
     data:
             vx = 3, 1, 4, 1, 5 ;
     }

which corresponds to a 92-byte netCDF file. The following is an edited dump of this file:

        4344    4601    0000    0000    0000    000a    0000    0001
       C   D   F 001  \0  \0  \0  \0  \0  \0  \0  \n  \0  \0  \0 001
       17220   17921   00000   00000   00000   00010   00000   00001
     [magic number ] [  0 records  ] [NC_DIMENSION ] [ 1 dimension ]
     
        0000    0003    6469    6d00    0000    0005    0000    0000
      \0  \0  \0 003   d   i   m  \0  \0  \0  \0 005  \0  \0  \0  \0
       00000   00003   25705   27904   00000   00005   00000   00000
     [  3 char name = "dim"        ] [ size = 5    ] [ 0 global atts
     
        0000    0000    0000    000b    0000    0001    0000    0002
      \0  \0  \0  \0  \0  \0  \0 013  \0  \0  \0 001  \0  \0  \0 002
       00000   00000   00000   00011   00000   00001   00000   00002
      (ABSENT)     ] [NC_VARIABLE  ] [ 1 variable  ] [ 2 char name =
     
        7678    0000    0000    0001    0000    0000    0000    0000
       v   x  \0  \0  \0  \0  \0 001  \0  \0  \0  \0  \0  \0  \0  \0
       30328   00000   00000   00001   00000   00000   00000   00000
      "vx"         ] [1 dimension  ] [ with ID 0   ] [ 0 attributes
     
        0000    0000    0000    0003    0000    000c    0000    0050
      \0  \0  \0  \0  \0  \0  \0 003  \0  \0  \0  \f  \0  \0  \0   P
       00000   00000   00000   00003   00000   00012   00000   00080
      (ABSENT)     ] [type NC_SHORT] [size 12 bytes] [offset:    80]
     
        0003    0001    0004    0001    0005    8001
      \0 003  \0 001  \0 004  \0 001  \0 005 200 001
       00003   00001   00004   00001   00005  -32767
     [    3] [    1] [    4] [    1] [    5] [fill ]
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Generated on Tue Aug 6 2013 11:40:57 for netCDF. NetCDF is a Unidata library.