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1) The 'grid2shp' serializer can only output one time step so in case the grid is part of a timeseries the relativeViewperiod needs to be set to select a range of which only the first timestep will be used.
2) A prefix or suffix can be added to the filename using a time formatting string as in the given example. The timestamp will reflect the time at which the file was exported, not the exported time step which was selected using the given relativeViewPeriod.
3) The exportMissingValue can be used to replace the given missing values by NaN (Not A Number) values to indicate that there is no valid data, ArcGIS will display such records as '0' instead of -999 in this example.