/GrADS/script/cutdata.gs
/ 
cutdata
input-ctl output-grd
[-x xmin xmax]
[-y ymin ymax]
[-z zmin zmax]
[-t tmin tmax]
[-t timestep-range | -time timemin tmimeax | -time time-range]
[-var vname1,vname2,...]
[-undef undefined-value]