[gradsusr] opening Multiple grib2 files using single control file

[Syed Ahsan Ali]

I have grib2 forecast files from 0 to 174 hrs having variable time
steps, 0 to 78 hours have 3-hourly files and next 6-hourly. I am using
g2ctl.pl to make grads control file. It writes control file with equal
3 hour time steps. It couldn't differentiate between 3-hour and 6-hour
intervals present in the files. How can I make a control files having
variable time intervals?

Ahsan