This feature gives you the ability to:
Why would you want to change a date of an existing holiday? One example is where the holiday lands on a Sunday, but is celebrated on the following Monday. Many retail outlets may want to be able to compare apples to apples.
If you double click on any of the entries above you will get the following window:
is requesting access to a wiki that you have locked: https://clearify.com/wiki/view/223/date-setup-holiday-definitions