2009 Unidata NetCDF Workshop for Developers and Data Providers > The "Classic" NetCDF Data Model
4.8 Introducing CDL (Common Data Language)
CDL (Common Data Language) is text notation for netCDF objects and
data. It will be used for examples during the workshop.
netcdf example { // example of CDL notation
dimensions:
x = 3 ;
y = 8 ;
variables:
float rh(x, y) ;
rh:units = "percent" ;
rh:long_name = "relative humidity" ;
// global attributes
:title = "simple example, lacks some conventions" ;
data:
rh =
2, 3, 5, 7, 11, 13, 17, 19,
23, 29, 31, 37, 41, 43, 47, 53,
59, 61, 67, 71, 73, 79, 83, 89 ;
}
This example
specifies a netCDF dataset with two dimensions (x and
y), one variable (rh), two
variable attributes (units and
long_name), one global attribute (title), and some data values for
the variable.
- This example has only one variable, but multiple variables
may be included in a netCDF file.
- CDL comments follow "//" symbols. They are not part of netCDF
data.
To store comments about a variable or file, use a
variable attribute or global attribute.
- You can use the ncdump utility to get the CDL
form of a binary netCDF file (more on this later).
- You can use the ncgen utility to generate a
binary netCDF file from CDL (more on this later).
- This simple example neglects some recommended best practices for
netCDF data.
- NcML is an XML-based notation similar to CDL for netCDF data
2009 Unidata NetCDF Workshop for Developers and Data Providers > The "Classic" NetCDF Data Model