or… if you want the future time stamp to be “exactly x seconds” in the future you can store a tuple of the TAI time stamp of when you create the data point, an

or… if you want the future time stamp to be “exactly x seconds” in the future you can store a tuple of the TAI time stamp of when you create the data point, and the SI seconds into the future from that time and then render it as appropriate for the audience’s level of understanding And if you want the future time stamp to be not actually a time stamp but a time of day on a calendar date, then you store a tuple of the TAI creation time, the UTC date you want it to be in the future Because you can never ever be sure of the future, by keeping the time you make the assumptions you can at least either calculate the correct answer or fix the data later when you find out something has changed. TAI is for timekeeping. UTC is for calendars.