The client might be a desktop app, a smartphone, a web browser (maybe in a public library, where they don't control the locale...), or just an SMS receiver. The

The client might be a desktop app, a smartphone, a web browser (maybe in a public library, where they don't control the locale...), or just an SMS receiver. The only reliable place to apply these things is on the server, where you can look up the location of the appointment or event, and the preferences of the user, and apply whatever skew is appropriate.