For each MIP experiment and for each EC-Earth3 model configuration and for each
model component (ifs, nemo, tm5, lpjg), a metadata template file has been
created in the trunk/runtime/classic/ctrl/output-control-files/ sub directories for
each experiment. For instance the metadata template file:
  trunk/runtime/classic/ctrl/output-control-files/cmip6/CMIP/EC-EARTH-AOGCM/cmip6-experiment-CMIP-historical/metadata-cmip6-CMIP-historical-EC-EARTH-AOGCM-ifs-template.json
is the one for the CMIP historical experiment for the EC-EARTH-AOGCM model
configuration for the IFS component.

The metadata templates are generated by genecec's modify-metadata-template.sh
script.

Though most metadata should be correct, it is strongly recommended to check the
metadata template file. It is called a template because one has to adjust for
instance the ensemble member field:
    "realization_index":            "1",
depending on which member one is producing.

Further references to the meaning of the fields are:
 https://docs.google.com/document/d/16NTTxZM9l8B_tqLrG_zTJDGZYJr21dS7L3B-tGU2Wik/edit#
 https://cerfacs.fr/~coquart/data/uploads/cmip6_global_attributes_filenames_cvs_v6.2.6.pdf
