These fields will break down the Time_Period field into Year, Month, Day, or Hour depending on which options were selected in the Output Reporting Options portion of the Table Selection form of Simulation Options. 

For instance, if output for Month was selected, then there would be a Report_Month and a Report_Year field populated in the output table.

These fields are helpful for sorting and filtering.

Available Report Time_Periods:

Report_Year - The year of the time period.

Report_Month - The month of the time period.

Report_Day - The day of month of the time period.

Report_Hour - The hour of day of the time period.