August 12, 2014
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You’d be surprised to know how many Tinderbox support queries we receive concerning historical dates. I remember one month where it seemed every day brought a new question about dates more than a thousand years back.

Date conversions seems straightforward. The user types a string "August 12, 2014" or “8/12/14” and the system converts it to whatever internal representation it uses.

Of course, “8/12/14” in England means “December 8”. So, we need to know where you are. In Sweden, we’d write “2014–08-12” with dashes in place of slashes. In Germany, we’d use periods and write “12.8.14.” So things get a little bit complicated.

Where life really gets tricky is for historic dates. We all agree that the day begins at midnight, but that wasn’t always true; for lots of history, the new day began at sunset. Does OS X treat sunset, or 6PM, as the end of the day for some periods?

Until 1752, New Year’s Day in Britain was March 25. This means that the day Shakespeare knew perfectly well to be 5 January 1602 falls in the year that we ca;; 1603. If you’re using the Gregorian calendar, does OS X adapt dates prior to the adoption of the Gregorian calendar?

Some aspects of the calendar depend on where you are, but of course historians often study people who lived somewhere else. If you’re in Princeton, New Jersey but you’re writing about Pharsala, I assume that all the date conventions we use are those of the US (and, before then, of England).

I ask because, for some Tinderbox users, some historic dates have an off-by-one-day error. Or, perhaps Tinderbox is right, and we’re making a bad assumption. Surely this all is documented somewhere. But where?

If you know where this is documented, please Email me.