how to write a ASCII file by GrADS

[Hao He]

Hi,
    I used GrADS to read the GRIB file and wanted to selected some
variables, which can be write to an ASCII (.txt or .dat) file. I read the
manual and found I should use 'gxout fwrite'. But I still could not
figure out how to write the script. Does anyone have an idea?

Thanks!

Hao