This returns whether or not the given Date and Time is within working hours, according to the calendars defined for the system.
calisworktime( datetime, [calendar name] )
datetime: (Date and Time) The Date and Time to test.
calendar_name: (Text) This optional parameter accepts the name of a system calendar; otherwise, the default calendar is used.
Boolean
Passing a calendar name allows you to validate working time using an alternate system calendar, if you have multiple calendars configured.
See also: Process Calendar Settings
calisworktime(datetime(2011,12,13,20,0,0))
returns false