The problem of computer date formats for Historians

Fascinating. Dates and dating systems get complicated fast. [Link]

The basic problem (that we’ll discuss in great detail below) is that the current specification requires the use of the so-called proleptic Gregorian calendar. Although that makes perfect sense in the modern age, it becomes progressively more pointless as we travel back in time, and somewhere in the late 16th century we reach the point that proleptic Gregorian dates become actively harmful to historical research.

The basic problem is that historians of the Middle Ages and earlier periods use Julian dates because that’s what the documents of that era use. If we’d map them to proleptic Gregorian dates, as the specification demands, they would be worse than useless in any kind of automatic search-and-compare system.

Hundreds of years’ worth of historical literature uses Julian dates if the people from the era it discusses did so, and therefore a system that uses proleptic Gregorian dates just doesn’t find any matches.

The current specification acknowledges this problem — somewhat. It says:

For dates before the introduction of the Gregorian calendar, authors are encouraged to not use the time element, or else to be very careful about converting dates and times from the period to the Gregorian calendar

A literal interpretation would have odd consequences. If I’d write about the secret negotiations between Louis XIV and Charles II to destroy the Dutch Republic in the early 1670s, I would be allowed to mark up the dates of Louis XIV’s letters, but not those of Charles II’s ones. France used the Gregorian calendar back then, but England stuck to the Julian. Such a rule is useless for historians. Besides, it’s just plain weird.

As to marking up Charles II’s letters with Gregorian dates, that’s possible, but it could lead to the same problems we discussed above: the generally accepted date for a letter might be Julian, in which case an automated search for the Gregorian date misfires dramatically.

So I believe this remark is incorrect and should be changed. The specification should clearly and unambiguously state whether or not the element is fit for historical use instead of trying to find a vague formula that avoids this basic question. (I don’t even understand why this question should be avoided. It’s a simple one, though the consequences of a Yes are pretty complicated.)