This page was really discussion the question of OrderingIntervals rather than specifically ordering date ranges. I've taken the question as originally intended and put the discussion on a more accurately named page.  This page has the bit(s) that really relies on the discussion being about dates.

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When discussing date - which time zone?  Without a specified time zone, a date represents a 48-hour range. In addition to the general DateRange problem:
* What does it mean to say that two dates are the same if they come from different time zones?
* What does it mean to say that two times from different time zones fall on the same date? Is it always possible to decide whether they do or not?
* In general, are dates from different time zones comparable at all?

-- MarcThibault