dimensions:
    lat = 180 ;
    lon = 360 ;
    pres = 15 ;
    time = unlimited ;
  variables:
    float xwind(time, pres, lat, lon) ;
      xwind:long_name = "zonal wind" ;
      xwind:units = "m/s" ;
    float lon(lon) ;
      lon:long_name = "longitude" ;
      lon:units = "degrees_east" ;
    float lat(lat) ;
      lat:long_name = "latitude" ;
      lat:units = "degrees_north" ;
    float pres(pres) ;
      pres:long_name = "pressure" ;
      pres:units = "hPa" ;
    double time(time) ;
      time:long_name = "time" ;
      time:units = "days since 2000-1-1 0:0:0" ;
  

xwind(n,k,j,i) is associated with the coordinate values lon(i), lat(j), pres(k), and time(n).