I am trying to create a validation rule which does allow a user to make an incident due on Sundays. The easiest way that I can think of is to set it so that when datepart(weekday,workitem_due_on) = 7 there is an issue. since Sunday is represented by a 7. However, the validation rules do not like datepart but prefer FORMAT_DATETIME(datetime, output_format, input_format). I have no idea how to use this macro nor can i even find an example of it in use, can somebody please advise how I would simply be able to return the day of the week in a validation rule? Thanks