[mzl]

I'd say, in general any time a time-value somehow originates as a part of an interaction with a human, that time-value carries with it the context of a timezone and the expectations of what that timezone means for that human.

For internal timestamps such as ordering events in a database, them UTC or something similar is nice. Bet the point then is that those values are not really meaningful or important in the analog world.

[sfn42]

Pretty much everything most user-facing apps do generates time values. Maybe it's more accurate to say any time a user actually inputs a date and time. Stuff like scheduling and booking software definitely needs to consider these things.

Basically if you want to preserve the original input then obviously you won't change it. If you just want to record an instant in time you use UTC.