Calendar
Dates worth seeing above a week: holidays, property closures, company events. They are shown as a banner across the top of the affected week; nothing here stops anyone being scheduled on those days.
Adding one
Give it a title, a kind - Holiday, Closure or Event - and a start date, with an optional end date for anything longer than a day. It shows up under Coming up until its date passes, then moves to Gone by.
Shared events
US federal holidays are seeded in for you and marked shared, the same as anything a property added for every scheduler to see; shared events can't be removed from this page, since more than one person relies on them. Anything you add yourself, you can take back off.