Page History

In general it is organised, as a huge tree, with the indentation below, showing different levels down that tree:

• centre (CMA, ECMWF, NCEP, JMA, ...)
  • realtime or reforecast
    •  type of data (control forecast or perturbed forecast)
      • type of level (single level or pressure level or potential  temperature)
        • ModelVersionDate model version date (2014-05-01 or ...)
          
          • HindcastDates hindcast dates (2014-01-01 or 2014-01-02 or 2014-01-03, ...)
            •  time-steps
              • members (for perturbed forecast)
                • levels (for pl or pt)
                  • parameters

The idea is to request as much data as possible from the same tape file, all time-steps, all members, all parameters for a type of level, a type, a HindcastDatehindcast date

Following the previous paragraph,  the natural way to group requests would be:
all parameters, all levels, all members, all time-steps for 1 HindcastDatehindcast date.

Note the following:

1. 'all' means 'all' that the user wants. It doesn't have to be all parameters.
2. If a user is interested only on z500,  he may request more HindcastDates hindcast dates in one go, since the overall request will not be so big.