MARS

Specifies the ECMWF classification given to the data.

class=<value>

Archived data may originate from e.g. routine operations (od), from research experiments (rd), reanalysis data sets (e.g. ea for ERA5), TIGGE (ti) , S2S (s2) or experiments created by Member State users (Internet country code, e.g. uk, es,...). Operations and reanalysis are the most frequently used data classes. A full list of ECMWF classes is available online.

Example: 

retrieve,                            # 2 m temperature fields from operational analyses
 class=od,                           # at all synoptic time on 1st September 2018.
 date=2018-09-01,
 expver=1,
 levtype=sfc,
 param=167.128,
 stream=oper,
 time=00/06/12/18,
 type=an,
 target="output"

Dissemination

The only supported option is class=od (operational data)