The authority that declares a closure — which is not always a country.
A jurisdiction here is the authority competent to declare a closure. That is deliberately narrower than country and deliberately wider than state.
Narrower, because a country is a political claim and this is an administrative one. The corpus holds Hong Kong, Taiwan, the Falklands and Saint Helena. Calling them countries is contested where it is not simply wrong — an SAR and an overseas territory are not states — while jurisdiction is the precise word for what is actually recorded: somebody publishes closures for that place.
Wider, because Bavaria, Catalunya and Scotland each set days their national government does not. A calendar organised by country cannot represent them, which is why asking for GB returns the United Kingdom's national list and not Scotland's.
Listing a jurisdiction is a statement that an authority publishes closures for it. It is not a position on sovereignty, recognition or status.
Every country is a jurisdiction. Not every jurisdiction is a country — subdivisions, territories and special administrative regions all publish their own closures.
See also observance · assurance · public holiday
We hold this as the jurisdictions table — 241 top-level and 653 subdivisions. See what we hold.