Use the AddNonworkingDate method to define specific dates as non-working days. To mark recurring days within a week (such as every Saturday and Sunday), use the NonworkingDays property. To remove a date previously added with AddNonworkingDate, call RemoveNonworkingDate (it only removes dates added through that method). To clear all custom non-working dates at once, use ClearNonworkingDates.

You can control how non-working days appear using:

• NonworkingDaysPattern,  sets the fill pattern for non-working days
• NonworkingDaysColor, sets the fill color for non-working days

Examples of repetitive expressions

• "month(value) = 7", marks the entire month of July as non-working
• "shortdateF(value) left 5 in ('01/01','01/06','04/25','05/01','06/02','08/15','11/01','12/08','12/25','12/26')", marks specific fixed calendar dates such as Jan 1, Jan 6, Apr 25, May 1, Jun 2, Aug 15, Nov 1, Dec 8, Dec 25 (Christmas), and Dec 26.
• "month(value) = 1 and (day(value) in (1,6))", marks January 1 and January 6.
• "not(month(value) in (3,4)) ? 0 : ( floor(value)=floor(date(dateS('3/1/' + year(value)) + ((1:=(((255 - 11 * (year(value) mod 19)) - 21) mod 30) + 21) + (=:1 > 48 ? -1 : 0) + 6 - ((year(value) + int(year(value) / 4)) + =:1 + (=:1 > 48 ? -1 : 0) + 1) mod 7))))", Easter day:
• "not(month(value) in (3,4,5)) ? 0 : ( floor(value)=(2:=floor(date(dateS('3/1/' + year(value)) + ((1:=(((255 - 11 * (year(value) mod 19)) - 21) mod 30) + 21) + (=:1 > 48 ? -1 : 0) + 6 - ((year(value) + int(year(value) / 4)) + =:1 + (=:1 > 48 ? -1 : 0) + 1) mod 7)))) or (floor(value)= =:2 + 1))", Easter Sunday and the following day

The expression syntax supports predefined functions as documented here. In all expressions, the value keyword represents the date being evaluated.