Use Date if the lookup table or relationship you need to define is constant or varies as a function of the time of year or season.

The independent variable Date needs no further definition so its edit panel in the Independent Variable Definition dialog is blank.

After you select Date and click OK to accept that selection and close the Independent Variable Definition dialog, a seasonal function table will appear in the editor you came from. The seasonal function table will have Date in the header of the first column and the first cell below the Date header will contain the value 01Jan. Any additional dates needed for your function should be entered in the form DDMMM, where DD is a two-digit day of month and MMM is a three-character abbreviation for the month. Function-of-Date relationships in ResSim repeat annually and always begin on 01 January, so no year specification is included in the date. If your relationship is constant, only one row of the table is required—just enter your constant value in the 01Jan row.

All seasonal tables in ResSim treat each date entered as the beginning of the day, i.e., as applying at 0000 hours. If you would prefer that your dates in the Function-of-Date table applied at the end of the day, use the next day in the table or define your relationship (table) as a Function-of-Date-and-Time.