[whatwg] Expanding datetime

[Henri Sivonen]

On Apr 25, 2008, at 04:34 , Charles McCathieNevile wrote:

> As an historian, these seem useful things to be able to do. It would  
> seem to me as a browser maker that this doesn't actually complicate  
> life a whole lot (I may be wrong - I haven't thought hard about the  
> implications yet). As a standards guy, I do not see that being able  
> to do this would introduce any particular complications (beyond a  
> few more test cases). I am inclined to think that the use cases  
> justify the cost, at least enough to investigate further.


I think the questions are:
  * Are there use cases for entering proleptic Gregorian dates before  
the Common Era in a Web form (<input type=date>)?
  * Are there use cases for representing proleptic Gregorian dates  
before the Common Era in a way that moving the data to a calendar app  
(<time>)?
  * Are there use cases for  annotating document modifications with  
proleptic Gregorian dates before the Common Era (<ins>/<del>)?

I think the answer to the ins/del case is "no". The future is intended  
for tracking changes in computer documents, and all historical  
documents have been migrated to computer documents in the Common Era.

I think the answer to the calendar at case is in "no". The calendar  
app case is about planning future events. You don't need <time> markup  
when writing about historic events before the Common Era--in  
particular, if you write about events that are referred to by their  
Julian dates.

As for the form case, it seems implausible to me that sites about the  
history of urban planning or ecology would require users to enter  
dates that are more precise than to the year. In the case of sites  
about historic events, it also seems implausible that users would be  
competent to enter precise proleptic Gregorian dates for searching  
events that occurred when the Julian Calendar was in use (or in other  
locales a calendar that *looks* different, too).

To make calculations with the precision of a year, the user interface  
could use a form field that takes a number and sidestep the issue of  
converting the year two seconds or milliseconds.

The historic astronomy case seems awfully narrow to justify making  
native date widgets deal with BCE dates.

-- 
Henri Sivonen
hsivonen at iki.fi
http://hsivonen.iki.fi/