The Duration setting of recurrence rule used is specified in the Duration panel of the recurrence rules tab control.
The Duration recurrence options lets you specify that a holiday lasts for more than one day.
example of the use of the DAY holiday name variation keyword with a multi-day holiday
The name of the recurring holiday will be the same for all dates, unless the name contains tokens, or uses the DAY holiday name variation keyword, in which case the name of a multiday holiday might differ on each of the multiple days.
If Holiday A conflict rules point to Holiday B, and Holiday B lasts for more than one day, then a conflict will be noted if the date of Holiday A corresponds with any of the dates of Holiday B.
As usual, the exception to rule setting overrides all other settings including holiday duration. If you have an exception to rule that lasts for more than one day, then you should enter each individual date into the exception to rule editor.
See also: holiday names variations.