It is not, if what the user expects to stay constant is their local calendar/wall clock time rather than the UTC instant. Which is usually the case. This is a t

It is not, if what the user expects to stay constant is their local calendar/wall clock time rather than the UTC instant. Which is usually the case. This is a transformation that needs late binding as DST and timezone rules can change, so it can't just be handled as a localisation transformation on input/output