[csirac2]

Yes, from a data modeler's perspective it is definitely orthogonal.

From an evidence-based perspective though, a full "chain of custody" has to be maintained (as far as alterations go), providence of information can be very important.

If you care about reproducibility, how raw data has been manipulated from the original, you'd better have some record of it.

For date-times almost all public datasets standardize on ISO8601. Any datetimes captured by persons or processes which aren't working in UTC from the very beginning will have the TZ offset in it.

Normalizing to UTC is up to the data consumer to do as they please, but some get very upset if you try to say that an event was recorded as happening at 03:00 if the person or process actually recorded 13:00+10:00. It may seem subtle and boring and pointless, but the fact is that you may be seen to be changing the facts.