Sometimes it is required to scroll back in history and quote a statement made in a MUC earlier as described here:
Furthermore, it is useful to add date and time to the quote header indicating the time the statement was made,
esp. after several days back in time.
This allows other participants can scroll back in time to see the context close to the statement.
on 2020-08-29 at 15:12 UTC:
quoted statement here
Own response here
If the quoting person does not want not to give away his own timezone
the date should in in ISO 8601 and time should be in UTC.
If the quoting persion wants to do it, date and time can be in his local date/time format.
This requires a switch in the security settings. Date and time for quotes in local time or UTC.
Instead of the date the words today and yesterday are useful when applicable.