Thanks Vincent. I’d put a tentative task on my Calendar for today surmising that would be the answer: “Import Holidays” 
If I could impose further… Do you stilljust use CalDavCommand? Could you provide an example of one of your calendar holiday entries?
I can see how the Command can trigger to set that a holiday has begun. I suppose one could configure a holiday entry to “turn on early” to have openHAB “see” the upcoming holiday. But I’m going to play around with the Personal binding to try to “see ahead” for upcoming holidays because I need the day transitions for my HVAC schedule to take holidays vs. workdays into account.
Mike