Or if you really want to be future proof, store the geolocation so you can try to figure out the jurisdiction for any changing regulations. Maybe they didn't ch

Or if you really want to be future proof, store the geolocation so you can try to figure out the jurisdiction for any changing regulations. Maybe they didn't change the date of the switch, but changed the timezone boundary on the map. But, then I guess we might need to account for fractured societies and actually store some kind of organizational code for which belief system the event author adheres to? :-)