sdfopen filename <template #timesteps>
Opens a NetCDF or HDF-SDS format file that conforms to the COARDS conventions. The sdfopen command does not support the HDF5 format, but is does support netcdf4. The arguments and options are as follows:
filename  
  template  
  template 
    has a similar structure to the substitution template in a GrADS data descriptor 
    file. See Using Templates for details.  
  #timesteps  
  template 
    is invoked. The #timesteps is the sum of the timestep 
    counts in all the files to be examined, not the count in any one file.  
  
| GrADS Dimension | Acceptable Attribute Values | 
| X | units: degrees_east, degree_east, degrees_E, degree_E axis: x, X | 
| Y | unit: degrees_north, degree_north, degrees_N, degree_N axis: y, Y | 
| Z (pressure) | units: mb, millibar, hybrid_sigma_pressure | 
| Z (not pressure) | units: sigma_level, degreesk, degrees_k, level, layer, layers axis: z, Z | 
| T | units: yyyymmddhhmmss, yymmddhh, or a Udunits-acceptable time unit axis: t, T | 
| E | grads_dim: e axis: e, E | 
xdfopen 
    command which requires a special descriptor file to supplement or override the metadata in the file, or use the open command with a complete descriptor file. 
uwnd.1989.nc 
    and uwnd.1990.nc, you could access them both as one GrADS data 
    set by entering: 
    
sdfopen /data/uwnd.1989.nc uwnd.%y4.nc 730