For an absolute event that was observed, UTC is, indeed, correct. For anything interacting with planning though, the user's needs should be considered. Often

For an absolute event that was observed, UTC is, indeed, correct. For anything interacting with planning though, the user's needs should be considered. Often what you actually want to store is a "recurrence rule" for a single event, while being sure to include the defining aspects picked, or at least confirmed, by the user.