Withe the Shared Calendar, holidays can be added and then used in Tide Dimensions.
The editing has following parts:
Add holiday(s):
Remove added holiday(s):
Edit name/comments:
Import holidays:
If you e.g. have a list of holidays in e.g. MS Excel, these can be imported. Copy the list to the clipboard. The list must at least have on date column. It can have columns for date, name and comment.
Copy holidays:
Existing holidays from one year can be copied to another.