This field defaults to the day set in the FIRDAY-First day of the week parameter value (TPS chapter, MIS group).
The date in the Time start column in the Datestable is set automatically based on this value.
You cannot update this field, but you can manually change the date in the Time start column. In which case, the First day of the week field automatically changes to the weekday of the date entered in the Time start column.
Example:
First day the of the week (field FIRDAY) = Wednesday
Time start column (field STR1) = 02/22/2017
You set this date to 02/21/2017.
The day in the First day the of the week field is automatically set to 'Tuesday'.