[Veserv]

You record a context sensitive date/condition based on the user intent (i.e. birthday travels with the user, in person meeting based on meeting location, international call based on local time or UTC, explicit timezone keeps the timezone, etc.). How you map user intent to recorded date is problem specific.

When the event happens you record the TAI. You may also wish to record the context sensitive date for auditing purposes, but it is not strictly necessary. You can rederive the occurred date if the event occurred in the past.