That is outside of the scope of the article. In this case you have to ask yourself. Do you want to save an appointment for 18:30 in Chile? Or for the Superbowl?

That is outside of the scope of the article. In this case you have to ask yourself. Do you want to save an appointment for 18:30 in Chile? Or for the Superbowl? You have to choose one. If you really want to be sure tell your friends to use the timezone of the event. Maybe say "let's meet at 19:00 New York time" if the game starts at 20:00 in New York and you want to meet an hour before.