The MVDATE() function returns the multivalue style date value (days since 31 December 1967) for a supplied epoch value using the currently selected time zone.
An epoch value represents a moment in time. The MVDATE() function returns the date part of this as relevant to the currently selected time zone.
T = 1234567890
The above program fragment displays
The dates differ because this moment in time was 23:31:30 on 13 February 2009 in the GMT time zone but it was 11:31:30 on 14 February 2009 in the Pacific/Wake time zone.